ATP-sensitive K+ Channels in Cardiac Muscle from Cold-Acclimated Goldfish: Characterization and Altered Response to ATP
ATP-sensitive potassium channels (K ATP) play an important, if incompletely defined, role in myocardial function in mammals. With the discovery that K ATP channels are also present at high densities in the hearts of vertebrate ectotherms, speculation arises as to their function during periods of col...
Saved in:
Published in | Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Vol. 119; no. 1; pp. 395 - 401 |
---|---|
Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
1998
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | ATP-sensitive potassium channels (K
ATP) play an important, if incompletely defined, role in myocardial function in mammals. With the discovery that K
ATP channels are also present at high densities in the hearts of vertebrate ectotherms, speculation arises as to their function during periods of cold-acclimation and depressed ATP synthesis. We used single-channel and intracellular recording techniques to examine the possibility that channel activity would be altered in cardiac muscle from goldfish (
Carassius auratus) acclimated at 7 ± 1°C relative to control (21 ± 1°C). As previously observed in mammals, K
ATP channels in isolated ventricular myocytes were inwardly rectified with slope conductances of 63 pS. However, channel mean open-time and overall open-state probability (P
o) were significantly increased in cells from the cold-acclimated animals. In addition, K
ATP channels in cells from fish acclimated at 7° were nearly insensitive to the inhibitory effects of 2 mM ATP, whether studied at 7 or at 21°C. Transmembrane action potential duration (APD) in hearts of cold-acclimated fish studied at 21° was significantly shorter than that observed in hearts of warm-acclimated fish at the same temperature; this difference was eliminated by the K
ATP channel antagonist glibenclamide (5
μM). These data suggest that K
ATP channels in the hearts of cold-acclimated animals are more active and less sensitive to ATP-inhibition than those in warm-acclimated fish, possibly reflecting a functional adaptation to promote tolerance of low temperatures in this species. |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1095-6433 1531-4332 |
DOI: | 10.1016/S1095-6433(97)00443-1 |