Navigation Links
Penguins continue diving long after muscles run out of oxygen
Date:5/11/2011

Breathing heavily at the edge of an ice hole, an Antarctic emperor penguin prepares to dive. Taking a last gulp of air, the bird descends and may not emerge again for another 20 minutes. The penguin initially carries sufficient oxygen in three stores the blood, lungs and myoglobin in muscle to sustain aerobic metabolism. However, around 5.6 minutes after leaving the surface, lactate begins appearing in the penguin's blood and the bird crosses the so-called 'aerobic dive limit', switching to anaerobic metabolism in some tissues. So what triggers this transition?

Cassondra Williams from the Scripps Institution of Oceanography explains that the animals were thought to cross the aerobic dive limit when one of their three oxygen stores became exhausted. However, when Paul Ponganis measured oxygen levels in the blood and lungs of penguins after long dives, the animals had oxygen to spare. That only left the muscle as the potential trigger. Williams explains that diving animals were thought to isolate their muscle from the circulatory system, leaving oxygen stored in the tissue as its only source of aerobic metabolism while submerged and forcing it to switch to anaerobic respiration once the supply was exhausted. So, she and Ponganis teamed up with Jessica Meir to travel to Antarctica to measure muscle oxygen levels in diving emperor penguin muscles and they publish their discovery that depleted muscle oxygen supplies trigger the aerobic dive limit in The Journal of Experimental Biology at http://jeb.biologists.org/content/214/11/1802.abstract.

However, before their departure, Williams had to design a near-infrared spectrophotometer to record the penguins' muscle oxygen stores as they dived in the wild. After two trying years of technical development and testing, Williams was able to travel south with her colleagues to surgically implant the spectrophotometers in the pectoralis muscles of emperor penguins. They also attached timedepth recorders to the animals' backs to track their dive profiles. Finally, the team ensured that the animals would return with their precious equipment by drilling an isolated hole in the sea ice to which the penguins were guaranteed to return before releasing the implanted animals to go foraging for a day or two.

After successfully retrieving all of the spectrophotometers and dive recorders and returning the penguins to their colony, Williams began analysing the data and found that the penguins had been actively foraging beneath the ice. Of the 50 dives that Williams successfully recorded, 31 exceeded the emperor penguin's calculated dive limit.

Next, Williams plotted the muscle oxygen profiles over the course of each dive and identified two distinct patterns. In the first, the oxygen levels fell continually, approaching zero around the point when the birds crossed the aerobic dive limit. Williams says, 'This profile certainly supports the hypothesis that muscle oxygen depletion is the trigger of the aerobic dive limit.'

However, when the team saw the second pattern, they were surprised that, after initially falling, the oxygen levels plateaued for several minutes before falling again to almost zero. They realised that blood must be flowing into the muscle to replenish the oxygen supply during the middle phase of the dive, delaying the onset of the aerobic dive limit.

Finally, having confirmed that the dive muscles are the source of the aerobic dive limit, Williams calculated the muscle oxygen consumption rate for dives with the first oxygen depletion pattern and was amazed to see that it was only 12.4ml of oxygen per kg of muscle per minute: 1/10th the value calculated for penguins swimming in an artificial flume and only 2𔃁 times their resting metabolic rate. 'I think this metabolic rate is impressive. You can see how hard they are working underwater but they are efficient swimmers and very hydrodynamic,' says Williams.


'/>"/>

Contact: Kathryn Knight
kathryn@biologists.com
44-787-634-4333
The Company of Biologists
Source:Eurekalert

Related medicine news :

1. SNMs Conjoint Mid-Winter Meetings continue to advance molecular imaging
2. Study finds racial gaps continue in heart disease awareness
3. American Heart Association Rapid Access Journal Report: Study Finds Racial Gaps Continue in Heart Disease Awareness, Low Knowledge of Heart Attack Warning Signs Among Women
4. Is a Tummy Tuck Right for Me? Alabama Plastic Surgeon Dr. David Durst Offers Tips as the Popularity of Surgical Cosmetic Enhancement Continues to Rise
5. United Capital continues to lead in funding
6. JPMA Supports CPSC Chairman Tenenbaum's Continued Safety Efforts
7. Demand For Mobile Prostate Cancer Brachytherapy Vendor Programs Continues Into 2010
8. SEIU ULTCW Commends CA Legislature for Measures to Narrow States Budget Gap While Calling for Continued Courage When Addressing the 2010/2011 State Budget
9. Xyngular™ Distributors Continue Waiting For Xyngular Xyng™ As Zija's XM3™ "Happy Pill" Reaches Record Sales
10. Coalition for Pulmonary Fibrosis and American Thoracic Society Continue Commitment to Pulmonary Fibrosis Research
11. CUTCO Cutlery Continues Its Support of Go Red For Women(R) into 2011
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/27/2016)... , ... June 27, 2016 , ... TopConsumerReviews.com recently awarded ... Eyeglasses . , Millions of individuals in the United States and Canada wear ... a way to both correct vision and make a fashion statement. Even celebrities use ...
(Date:6/26/2016)... ... June 26, 2016 , ... Pixel Film Studios Released ProSlice Levels, a Media ... give their videos a whole new perspective by using the title layers in ... Studios. , ProSlice Levels contains over 30 Different presets to choose from. ...
(Date:6/26/2016)... Birmingham, Lake Orion, Clarkston, Michigan (PRWEB) , ... ... ... their direction with respect to fertility once they have been diagnosed with endometriosis. ... for tolerable intercourse but they also require a comprehensive approach that can help ...
(Date:6/25/2016)... ... ... closing of Bruton Memorial Library on June 21 due to a possible lice infestation, as ... of head lice: the parasite’s ability to live away from a human host, and to ... one in the event that lice have simply gotten out of control. , As lice ...
(Date:6/25/2016)... ... ... As a lifelong Southern Californian, Dr. Omkar Marathe earned his Bachelors in ... School of Medicine at UCLA. He trained in Internal Medicine at Scripps Green Hospital ... at the UCLA-Olive View-Cedars Sinai program where he had the opportunity to train in ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... 24, 2016   Bay Area Lyme Foundation ... Dean Center for Tick Borne Illness , Harvard ... MIT Hacking Medicine, University of California, Berkeley, and ... the five finalists of Lyme Innovation , ... than 100 scientists, clinicians, researchers, entrepreneurs, and investors ...
(Date:6/24/2016)... 24, 2016 Research and ... "Structural Electronics 2015-2025: Applications, Technologies, Forecasts" report ... In-Mold Electronics, Smart Skin, Structural Health Monitoring, ... Structural electronics involves electronic and/or electrical components ... replacing dumb structures such as vehicle bodies or ...
(Date:6/24/2016)... Dehaier Medical Systems Ltd. (NASDAQ: DHRM ) ... medical devices and wearable sleep respiratory products in ... with Hongyuan Supply Chain Management Co., Ltd. (hereinafter referred ... to develop Dehaier,s new Internet medical technology business. ... Hongyuan Supply Chain,s sales platform to reach Dehaier,s dealers ...
Breaking Medicine Technology: