CHAPTER 2
In from the Cold
Argentinean Andrea Salas isn’t just pretty. She’s flat-out gorgeous. Although
no relation to the fashion model of the same name, she’s even more beautiful,
in my opinion. The glow of a summer sunset streaks her cascade of
auburn hair. Her caramel colored skin is flawless. Usually, when she speaks, her
doe eyes dance with merriment.
But not today.
Today she is dredging up memories of her brush with death in Antarctica.
The deep waters of the world’s most extreme environment threatened to take her
life. If the sea didn’t, the cold surely would have.
ALL ABOARD FOR THE ANTARCTIC
November 23, 2007. Andrea’s ship, the Explorer, had been at sea for thirteen
of its scheduled eighteen days of sightseeing along the margins of Antarctica.
Andrea, age thirty-eight, was a veteran Antarctic guide, having served on two
previous voyages. This time, as one of sixty-four crew members, she was working
as assistant to the leader of the expedition team. She organized lectures, wet landings,
and recreational activities for the Explorer‘s ninety-one passengers, a sixteennation
aggregate of intrepid tourists who had opened their wallets wide for this,
the adventure trip of a lifetime.
The ship had departed from Ushuaia, Argentina, a town that fights a perpetual
feud with Chile’s Punta Arenas over which is the southernmost city in the
world. The itinerary called for a stop in the Falkland Islands—the Malvinas to
the Argentineans—and a visit to an abandoned whaling station in South Georgia.
From there, Andrea and her shipmates traveled to Elephant Island, famous as
the last refuge of the men of Shackleton’s Endurance Expedition of 1914–1916.
Shackleton failed to cross the Antarctic continent on foot as he had planned, and
he was forced to leave his men on Elephant Island while he piloted a single
lifeboat across eight hundred miles of open ocean to find help on South Georgia.
The landscapes of the islands were breathtaking, Andrea recalls. Wildlife is
scarce in this, the most inhospitable environment on earth, but the tourists marveled
at the albatrosses of Steeple Jason in the Falklands. They oohed and aahed
over the king penguin rookeries of South Georgia.
November is early for an Antarctic trip. The sun doesn’t rise in Antarctica
until September, and summer doesn’t arrive until January when the weather
warms to a balmy –15° to –35°C (–5° to –31°F). The weather was exceptionally
cold on this trip. Andrea kept her charges wrapped in layers of thermal underwear,
polar fleece, and waterproof jackets. Boots swaddled feet, while waders cocooned
passengers toes-to-chest for wet landings. The season and the cold brought
with them some disappointments for the passengers and crew of the Explorer. A
planned side trip to South Orkney Island had to be canceled because the seas
were beginning to crowd with icebergs.
It might have been a portent, but the Explorer steamed on.
On this Thursday night, Andrea left her cabin on the crew deck, below sea
level. There, while resting in bed, she could hear ice hitting the hull. She wasn’t
worried. The Explorer was built to handle icy seas. She headed to the bar to enjoy
a drink with fellow crew members and some passengers. The bar was warm;
the drinkers, convivial.
ABANDON SHIP!
Around midnight two passengers rushed into the bar, shouting, “There’s
water! There’s water!” Everyone ran from the bar, only to collide with the captain
who was ascending the stairs. “The captain told us water was coming in
through a hole,” Andrea says. She raced to her cabin, as did the others, pulling on
warm clothes and collecting her life jacket, while the captain announced from
the bridge that emergency evacuation was commencing. “This is not a drill!”
“We got to the muster stations almost immediately,” Andrea reports. Huddled
there in the dark and biting cold, passengers listened to reassurances from
the captain over the public address system. Attempts were underway to repair the
hull, but just in case, emergency rescue stations in Chile and Argentina had
been radioed, as had other ships in the area. Andrea joined her fellow crew members
in distributing hot drinks and hope while awaiting the order to abandon ship.
It wasn’t long before that order came. Repair attempts had failed, and seawater
was pouring in through a breach in the hull. Its cause? Probably impact with an
iceberg.
Now came the greatest challenge: Andrea and 153 others would have to
brave the turbulent Antarctic seas and the bitter cold in nothing more than small
lifeboats and Zodiacs, the inflatable rubber boats usually employed for tendering
to shore from the ship and sightseeing along rocky coasts and beaches. Andrea
hustled passengers into the emergency craft, making sure that each boat had
a crew member to handle the motor and steering.
She and two other crew members lowered one of the Zodiacs into the water
and scrambled aboard. Zodiacs are not lifeboats, but in Andrea’s opinion, they
represented a better choice for escape than did Explorer‘s aging orange lifeboats,
which were heavy, clumsy, and poorly powered, although provisioned with food
and water. The Zodiacs have powerful motors; they are light and are highly maneuverable.
Still, they are open, small, and cramped when holding more than
four or five people.
Andrea’s Zodiac maneuvered next to one of the crowded, heavy lifeboats,
transferring seven passengers into the rubber inflatable. When all the boats were
in the water, the crew lashed the lifeboats and Zodiacs together with ropes, using
the Zodiacs’ engines to keep the lifeboats from ramming into icebergs. The
passengers and crew of the Explorer had radios that allowed communication
among themselves but not with the outside world. They were alone and adrift in
the Antarctic seas.
The ten people on Andrea’s Zodiac crouched under blankets, settling in for
a long wait. Mostly they all stayed silent, the smell of apprehension heavy in the
air. “Those were the longest hours of my life,” Andrea says. The wind whizzed
past her ears. The cold crept through her seawater-soaked clothing to ice her bones.
In conditions like these, she discovered, waterproof jackets aren’t waterproof.
“My feet and hands were very cold,” she says. “I never feared death, but I did
fear that I might lose a hand, a finger, a foot. I don’t know how cold it has to be
to lose a part of your body, but I was afraid it would happen because I knew I
would not get any warmer.” She and her compatriots were stacked in the Zodiac
like cord wood. They had no way to move, no means of generating or sharing
heat. “I couldn’t feel my hands inside my gloves,” Andrea says. “My feet were
blocks of ice.”
COLD-SENSING
While Andrea waited for rescue, she felt overwhelmed by a paralyzing sense
of cold in every part of her body. What gave her that feeling? What was going on
in her nervous system to create that perception? The answer lies in tiny receptors
on the membranes of neuronal projections that lie close to the skin’s surface.
It’s long been known that touch neurons specialize. Some respond only to
pressure; some, only to light touch. Several subsets of neurons fire an impulse
when the ambient temperature rises. Others detect only a decline—or cooling.
(Any temperature lower than that of the human body, 37°C or 98.6°F, is “cold”
in the physiological sense.) One type of neuron fires at relatively warm temperatures,
15° to 4°C (59° to 39°F); yet another type activates at temperatures below
0°C (32°F).1 Still another kind generates an impulse only when cold is so
intense that it’s painful.
For a long time, no one understood what was going on in temperaturedetecting
neurons, but that changed in 2002 when several research teams delivered
up two prizes: receptors on nerve cell membranes that respond to coolfeeling
chemicals such as menthol; and cold-activated ion channels in cell
membranes. The receptors work just as taste and smell receptors do; after locking
onto a molecule of a cool-feeling chemical, they provoke some change in
the cell that, in turn, triggers a nerve impulse. The channels do precisely what
their name suggests. They either open in response to cold, allowing ions (charged
atoms or molecules) to flow into the cell,2 or they close to prevent them from
leaking out—maintaining the cell’s positive charge.3
The influx of positively charged sodium or calcium ions (or the maintenance
of a positive charge) causes electrical potentials to change across the outer membrane
of the neuron. That happens because a neuron at rest has a slightly negative
charge inside it, compared with a positive charge outside. When cold causes
an ion channel to open, sodium ions flow into the cell, thus changing the charge
along its membrane. For a tiny fraction of a second, the inside of the cell becomes
positive; the outside becomes negative. This reversal in one tiny area creates a
current that affects the membrane farther along. Channels there open, and sodium
flows into another section of the nerve fiber, then another, then another. That’s
how the impulse travels—eventually to the brain.
Receptors and ion channels can work alone or in concert, in the same cell
or in different cells. One receptor channel called TRPM8 has been studied extensively.
Also called CMR1 (cold and menthol receptor 1), it’s a major player
in detecting gentle cooling. Researchers at the University of California at San
Francisco found its genetic base when they isolated cold-sensitive, mentholsensitive
neurons from rats. They took the TRPM8 gene from those cells and
placed it into cultured neurons that were neither cold- nor menthol-sensitive.
The cells changed their function and became cold- and menthol-detecting neurons.
Why? Because the gene directed the construction of TRPM8 receptors on
the cell membrane.Another team of researchers that same year discovered how cells that have
TRPM8 receptors respond to temperatures in the 23°C to 10°C (73° to 50°F)
range. The calcium concentration increases inside the cell. This suggests that
TRPM8 is both a receptor and an ion channel.5 The scientists don’t know how
cold affects the channel, but they describe two possible mechanisms. Cold might
change the shape of the channel directly, or it might trigger the release of a chemical
(a “second messenger”) that, in turn, prompts TRPM8 to open.
Another possible mode of action has been explored by researchers in Spain.
They studied “voltage-gated” potassium channels in cell membranes. Neurons
insensitive to cold have them, but cold-sensitive neurons do not. The channels
function as “excitability brakes” during cooling in insensitive cells. They stop an
impulse from beginning. Cold-sensitive neurons lack such voltage gates, so temperature
changes can initiate an impulse in them. This relationship was established
when the Spanish team blocked the action of the voltage-gated potassium
channels in cold-insensitive neurons. About 60 percent of the neurons began
firing impulses in the cold.10
The human body can differentiate a temperature change as small as a single
degree Celsius, but only a few heat- or cold-sensitive ion channels like TRPM8
are known. How can relatively few cellular structures account for such a finely
tuned capacity? The answer may lie in the ability of the channels to shape-shift.
In cell cultures, channels that respond to increases in temperature are known to
rearrange themselves by combining with other channels within their same structural
“family” (not TRPMs but another category called TRPVs). The resulting
complexes demonstrate characteristics intermediate between those of the “parent”
forms. Research teams can measure the intermediate electrical charges and
ion-gating properties of these “hybrid” channels. This ability to shuffle and recombine
means that the number and variety of channel types are large. Although
channels that respond to decreases in temperature have not been researched, it’s
likely that they, too, combine with others to form intermediate types. Whether
such channel complexes act as functional temperature sensors in living organisms
remains unknown.11
RESCUE!
Andrea never gave a thought to her TRP receptors. She had survival on her
mind.
As the wee hours of the morning gave way to a (blessedly) clear dawn around
3 A.M. (nights deliver less than three hours of darkness at this latitude in November),
Andrea and nine others watched from the safety of their Zodiac as the Explorer
began to list starboard. The Explorer‘s engines had failed, perhaps swamped
by water. The boat careened drunkenly with the swirling currents, powerless and
empty after the captain was the last to abandon his post. Explorer drifted toward
seas increasingly jammed with icebergs, driven by a rising wind. Before it sank
at the end of the day, the Explorer would be completely surrounded by pack ice.
Andrea remembers the noise. “The sound of a ship when it is breaking and
about to sink is just like in the movies,” she says, her dark-chocolate eyes wide
with the memory. “I could hear pipes breaking.” The eerie creak of twisting
metal assaulted her ears unceasingly as what passes for an Antarctic dawn brightened
into morning.
And yet they waited for hours more, hoping against hope for a rescue they
could not be sure would come.
Then the Norwegian cruise ship, the Nornodge, topped the horizon. Rescue!
The Zodiacs raced toward the Nornodge, with the slower lifeboats trailing behind.
“We didn’t mind getting wet anymore,” Andrea says, her eyes brightening
now that she can report a happy ending. Miraculously, not a single person suffered
injury—not even frostbite. The Nornodge doctor offered treatment to the
rescued sailors—all 154 of them. Only two took advantage of the offer.
Andrea recalls how her sense of lethal cold disappeared when the rescue ship
arrived. “When I stood to look at the Nornodge, all the heat returned to my body,”
she says. “The hope I gained from seeing it sent a wave of warmth through me.
It was the excitement of feeling safe. Knowing that it was over, I didn’t feel cold
anymore.”
In from the Cold
Argentinean Andrea Salas isn’t just pretty. She’s flat-out gorgeous. Although
no relation to the fashion model of the same name, she’s even more beautiful,
in my opinion. The glow of a summer sunset streaks her cascade of
auburn hair. Her caramel colored skin is flawless. Usually, when she speaks, her
doe eyes dance with merriment.
But not today.
Today she is dredging up memories of her brush with death in Antarctica.
The deep waters of the world’s most extreme environment threatened to take her
life. If the sea didn’t, the cold surely would have.
ALL ABOARD FOR THE ANTARCTIC
November 23, 2007. Andrea’s ship, the Explorer, had been at sea for thirteen
of its scheduled eighteen days of sightseeing along the margins of Antarctica.
Andrea, age thirty-eight, was a veteran Antarctic guide, having served on two
previous voyages. This time, as one of sixty-four crew members, she was working
as assistant to the leader of the expedition team. She organized lectures, wet landings,
and recreational activities for the Explorer‘s ninety-one passengers, a sixteennation
aggregate of intrepid tourists who had opened their wallets wide for this,
the adventure trip of a lifetime.
The ship had departed from Ushuaia, Argentina, a town that fights a perpetual
feud with Chile’s Punta Arenas over which is the southernmost city in the
world. The itinerary called for a stop in the Falkland Islands—the Malvinas to
the Argentineans—and a visit to an abandoned whaling station in South Georgia.
From there, Andrea and her shipmates traveled to Elephant Island, famous as
the last refuge of the men of Shackleton’s Endurance Expedition of 1914–1916.
Shackleton failed to cross the Antarctic continent on foot as he had planned, and
he was forced to leave his men on Elephant Island while he piloted a single
lifeboat across eight hundred miles of open ocean to find help on South Georgia.
The landscapes of the islands were breathtaking, Andrea recalls. Wildlife is
scarce in this, the most inhospitable environment on earth, but the tourists marveled
at the albatrosses of Steeple Jason in the Falklands. They oohed and aahed
over the king penguin rookeries of South Georgia.
November is early for an Antarctic trip. The sun doesn’t rise in Antarctica
until September, and summer doesn’t arrive until January when the weather
warms to a balmy –15° to –35°C (–5° to –31°F). The weather was exceptionally
cold on this trip. Andrea kept her charges wrapped in layers of thermal underwear,
polar fleece, and waterproof jackets. Boots swaddled feet, while waders cocooned
passengers toes-to-chest for wet landings. The season and the cold brought
with them some disappointments for the passengers and crew of the Explorer. A
planned side trip to South Orkney Island had to be canceled because the seas
were beginning to crowd with icebergs.
It might have been a portent, but the Explorer steamed on.
On this Thursday night, Andrea left her cabin on the crew deck, below sea
level. There, while resting in bed, she could hear ice hitting the hull. She wasn’t
worried. The Explorer was built to handle icy seas. She headed to the bar to enjoy
a drink with fellow crew members and some passengers. The bar was warm;
the drinkers, convivial.
ABANDON SHIP!
Around midnight two passengers rushed into the bar, shouting, “There’s
water! There’s water!” Everyone ran from the bar, only to collide with the captain
who was ascending the stairs. “The captain told us water was coming in
through a hole,” Andrea says. She raced to her cabin, as did the others, pulling on
warm clothes and collecting her life jacket, while the captain announced from
the bridge that emergency evacuation was commencing. “This is not a drill!”
“We got to the muster stations almost immediately,” Andrea reports. Huddled
there in the dark and biting cold, passengers listened to reassurances from
the captain over the public address system. Attempts were underway to repair the
hull, but just in case, emergency rescue stations in Chile and Argentina had
been radioed, as had other ships in the area. Andrea joined her fellow crew members
in distributing hot drinks and hope while awaiting the order to abandon ship.
It wasn’t long before that order came. Repair attempts had failed, and seawater
was pouring in through a breach in the hull. Its cause? Probably impact with an
iceberg.
Now came the greatest challenge: Andrea and 153 others would have to
brave the turbulent Antarctic seas and the bitter cold in nothing more than small
lifeboats and Zodiacs, the inflatable rubber boats usually employed for tendering
to shore from the ship and sightseeing along rocky coasts and beaches. Andrea
hustled passengers into the emergency craft, making sure that each boat had
a crew member to handle the motor and steering.
She and two other crew members lowered one of the Zodiacs into the water
and scrambled aboard. Zodiacs are not lifeboats, but in Andrea’s opinion, they
represented a better choice for escape than did Explorer‘s aging orange lifeboats,
which were heavy, clumsy, and poorly powered, although provisioned with food
and water. The Zodiacs have powerful motors; they are light and are highly maneuverable.
Still, they are open, small, and cramped when holding more than
four or five people.
Andrea’s Zodiac maneuvered next to one of the crowded, heavy lifeboats,
transferring seven passengers into the rubber inflatable. When all the boats were
in the water, the crew lashed the lifeboats and Zodiacs together with ropes, using
the Zodiacs’ engines to keep the lifeboats from ramming into icebergs. The
passengers and crew of the Explorer had radios that allowed communication
among themselves but not with the outside world. They were alone and adrift in
the Antarctic seas.
The ten people on Andrea’s Zodiac crouched under blankets, settling in for
a long wait. Mostly they all stayed silent, the smell of apprehension heavy in the
air. “Those were the longest hours of my life,” Andrea says. The wind whizzed
past her ears. The cold crept through her seawater-soaked clothing to ice her bones.
In conditions like these, she discovered, waterproof jackets aren’t waterproof.
“My feet and hands were very cold,” she says. “I never feared death, but I did
fear that I might lose a hand, a finger, a foot. I don’t know how cold it has to be
to lose a part of your body, but I was afraid it would happen because I knew I
would not get any warmer.” She and her compatriots were stacked in the Zodiac
like cord wood. They had no way to move, no means of generating or sharing
heat. “I couldn’t feel my hands inside my gloves,” Andrea says. “My feet were
blocks of ice.”
COLD-SENSING
While Andrea waited for rescue, she felt overwhelmed by a paralyzing sense
of cold in every part of her body. What gave her that feeling? What was going on
in her nervous system to create that perception? The answer lies in tiny receptors
on the membranes of neuronal projections that lie close to the skin’s surface.
It’s long been known that touch neurons specialize. Some respond only to
pressure; some, only to light touch. Several subsets of neurons fire an impulse
when the ambient temperature rises. Others detect only a decline—or cooling.
(Any temperature lower than that of the human body, 37°C or 98.6°F, is “cold”
in the physiological sense.) One type of neuron fires at relatively warm temperatures,
15° to 4°C (59° to 39°F); yet another type activates at temperatures below
0°C (32°F).1 Still another kind generates an impulse only when cold is so
intense that it’s painful.
For a long time, no one understood what was going on in temperaturedetecting
neurons, but that changed in 2002 when several research teams delivered
up two prizes: receptors on nerve cell membranes that respond to coolfeeling
chemicals such as menthol; and cold-activated ion channels in cell
membranes. The receptors work just as taste and smell receptors do; after locking
onto a molecule of a cool-feeling chemical, they provoke some change in
the cell that, in turn, triggers a nerve impulse. The channels do precisely what
their name suggests. They either open in response to cold, allowing ions (charged
atoms or molecules) to flow into the cell,2 or they close to prevent them from
leaking out—maintaining the cell’s positive charge.3
The influx of positively charged sodium or calcium ions (or the maintenance
of a positive charge) causes electrical potentials to change across the outer membrane
of the neuron. That happens because a neuron at rest has a slightly negative
charge inside it, compared with a positive charge outside. When cold causes
an ion channel to open, sodium ions flow into the cell, thus changing the charge
along its membrane. For a tiny fraction of a second, the inside of the cell becomes
positive; the outside becomes negative. This reversal in one tiny area creates a
current that affects the membrane farther along. Channels there open, and sodium
flows into another section of the nerve fiber, then another, then another. That’s
how the impulse travels—eventually to the brain.
Receptors and ion channels can work alone or in concert, in the same cell
or in different cells. One receptor channel called TRPM8 has been studied extensively.
Also called CMR1 (cold and menthol receptor 1), it’s a major player
in detecting gentle cooling. Researchers at the University of California at San
Francisco found its genetic base when they isolated cold-sensitive, mentholsensitive
neurons from rats. They took the TRPM8 gene from those cells and
placed it into cultured neurons that were neither cold- nor menthol-sensitive.
The cells changed their function and became cold- and menthol-detecting neurons.
Why? Because the gene directed the construction of TRPM8 receptors on
the cell membrane.Another team of researchers that same year discovered how cells that have
TRPM8 receptors respond to temperatures in the 23°C to 10°C (73° to 50°F)
range. The calcium concentration increases inside the cell. This suggests that
TRPM8 is both a receptor and an ion channel.5 The scientists don’t know how
cold affects the channel, but they describe two possible mechanisms. Cold might
change the shape of the channel directly, or it might trigger the release of a chemical
(a “second messenger”) that, in turn, prompts TRPM8 to open.
Another possible mode of action has been explored by researchers in Spain.
They studied “voltage-gated” potassium channels in cell membranes. Neurons
insensitive to cold have them, but cold-sensitive neurons do not. The channels
function as “excitability brakes” during cooling in insensitive cells. They stop an
impulse from beginning. Cold-sensitive neurons lack such voltage gates, so temperature
changes can initiate an impulse in them. This relationship was established
when the Spanish team blocked the action of the voltage-gated potassium
channels in cold-insensitive neurons. About 60 percent of the neurons began
firing impulses in the cold.10
The human body can differentiate a temperature change as small as a single
degree Celsius, but only a few heat- or cold-sensitive ion channels like TRPM8
are known. How can relatively few cellular structures account for such a finely
tuned capacity? The answer may lie in the ability of the channels to shape-shift.
In cell cultures, channels that respond to increases in temperature are known to
rearrange themselves by combining with other channels within their same structural
“family” (not TRPMs but another category called TRPVs). The resulting
complexes demonstrate characteristics intermediate between those of the “parent”
forms. Research teams can measure the intermediate electrical charges and
ion-gating properties of these “hybrid” channels. This ability to shuffle and recombine
means that the number and variety of channel types are large. Although
channels that respond to decreases in temperature have not been researched, it’s
likely that they, too, combine with others to form intermediate types. Whether
such channel complexes act as functional temperature sensors in living organisms
remains unknown.11
RESCUE!
Andrea never gave a thought to her TRP receptors. She had survival on her
mind.
As the wee hours of the morning gave way to a (blessedly) clear dawn around
3 A.M. (nights deliver less than three hours of darkness at this latitude in November),
Andrea and nine others watched from the safety of their Zodiac as the Explorer
began to list starboard. The Explorer‘s engines had failed, perhaps swamped
by water. The boat careened drunkenly with the swirling currents, powerless and
empty after the captain was the last to abandon his post. Explorer drifted toward
seas increasingly jammed with icebergs, driven by a rising wind. Before it sank
at the end of the day, the Explorer would be completely surrounded by pack ice.
Andrea remembers the noise. “The sound of a ship when it is breaking and
about to sink is just like in the movies,” she says, her dark-chocolate eyes wide
with the memory. “I could hear pipes breaking.” The eerie creak of twisting
metal assaulted her ears unceasingly as what passes for an Antarctic dawn brightened
into morning.
And yet they waited for hours more, hoping against hope for a rescue they
could not be sure would come.
Then the Norwegian cruise ship, the Nornodge, topped the horizon. Rescue!
The Zodiacs raced toward the Nornodge, with the slower lifeboats trailing behind.
“We didn’t mind getting wet anymore,” Andrea says, her eyes brightening
now that she can report a happy ending. Miraculously, not a single person suffered
injury—not even frostbite. The Nornodge doctor offered treatment to the
rescued sailors—all 154 of them. Only two took advantage of the offer.
Andrea recalls how her sense of lethal cold disappeared when the rescue ship
arrived. “When I stood to look at the Nornodge, all the heat returned to my body,”
she says. “The hope I gained from seeing it sent a wave of warmth through me.
It was the excitement of feeling safe. Knowing that it was over, I didn’t feel cold
anymore.”
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