Some ectothermic vertebrates show unusually good tolerance to oxygen shortage and it is therefore assumed that they might, as a defense mechanism, decrease number or activity of ion channels in order to reduce membrane leakage and thereby ATP-dependent ion pumping in hypoxia. Although several studies have provided indirect evidence in favor of this ‘channel arrest’ hypothesis, only few experiments have examined activity of ion channels directly from animals exposed to chronic hypoxia or anoxia in vivo. Here we compare the inwardly rectifying K+ current (IK1), a major leak and repolarizing K+ pathway of the heart, in cardiac myocytes of normoxic and hypoxic crucian carp, using the whole-cell and cell-attached single-channel patch-clamp methods. Whole-cell conductance of IK1 was 0.5 ± 0.04 nS/pF in normoxic fish and did not change during the 4 weeks hypoxic (O2 < 0.4 mg/l; 2.68 mmHg) period, meanwhile the activity of Na+/K+ATPase decreased 33%. Single-channel conductance of the IK1 was 20.5 ± 0.8 pS in control fish and 21.4 ± 1.1pS in hypoxic fish, and the open probability of the channel was 0.80 ± 0.03 and 0.74 ± 0.04 (P > 0.05) in control and hypoxic fish, respectively. Open and closed times also had identical distributions in normoxic and hypoxic animals. These results suggest that the density and activity of the inward rectifier K+ channel is not modified by chronic hypoxia in ventricular myocytes of the crucian carp heart. It is concluded that instead of channel arrest, the hypoxic fish cardiac myocytes obtain energy savings through ‘action potential arrest’ due to hypoxic bradycardia.
The Journal of Membrane Biology – Springer Journals
Published: Sep 18, 2003
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera