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:9/20/2017)... Raton (PRWEB) , ... September 20, 2017 , ... In ... Daily Brain Booster has already been receiving positive feedback from customers trying the product ... months. , Daily Brain Booster was developed by neurosurgeon Shawn Moore, MD, for ...
(Date:9/20/2017)... , ... September 20, 2017 , ... ... of older Americans at risk of price gouging for their prescription drugs, according ... (TSCL) . “Because Medicare isn’t negotiating on our behalf, there’s no consistency in ...
(Date:9/20/2017)... ... September 20, 2017 , ... ... “RECYCLED Ezekiel's Plan for Freedom from ADDICTION” is the creation of published ... the field of addiction and homeless services, including more than a decade of ...
(Date:9/20/2017)... ... ... “Psalms of Humidity”: is a fascinating depiction of daily struggles and the ... closer to God. “Psalms of Humidity” is the creation of published author, David Waldrop, ... his life are the very same things that have shaped him into the man ...
(Date:9/20/2017)... (PRWEB) , ... September 20, 2017 , ... “Monique”: ... into uncomfortable situations. “Monique” is the creation of published author, Colleen Crispi, has owned ... Since then Crispi has been involved in real estate and cooking. , “The ...
Breaking Medicine News(10 mins):
(Date:9/18/2017)... Mich. , Sept. 18, 2017  PMD Healthcare ... Specialty Pharmacy of Kalamazoo, Mich. , ... hub service that expedites and streamlines patient and provider ... PD 2.0, and wellness management services.  ... device used to measure lung function for a variety ...
(Date:9/12/2017)... LAKES, N.J. , Sept. 12, 2017  Consumer reviews on ... Embrace Hearing as the number one company for hearing aids, ... ReSound™ and fifteen other brands. ... Embrace Hearing Named #1 by Consumers For Hearing Aids ... Embrace Hearing is an online store that provides ...
(Date:9/9/2017)...  Eli Lilly and Company (NYSE: LLY ... for lasmiditan, an investigational, oral, first-in-class molecule for the ... compared to placebo in the Phase 3 SPARTAN study. ... Congress of the International Headache Society (IHC) in ... today demonstrate lasmiditan,s potential to reduce pain and provide ...
Breaking Medicine Technology: