Effect of temperature on sodium-calcium exchange in sarcolemma from mammalian and amphibian hearts.
We have investigated temperature dependence of Ca2+ uptake by the cardiac sarcolemmal Na(+)-Ca2+ exchanger from dog, rabbit and bullfrog. In native rabbit sarcolemmal vesicles, Ca2+ affinity of the Na(+)-Ca2+ exchanger is unchanged from 7 to 37 degrees C; however, the initial velocity of Ca2+ uptake declines much more steeply below 22 degrees C than above 22 degrees C. In native dog sarcolemma, the temperature dependence of Na(+)-Ca2+ exchange velocity is similar to that of native rabbit. However, in frog heart the velocity of Na(+)-Ca2+ exchange declines much more slowly with decreasing temperature at both temperature ranges. Reconstitution of the Na(+)-Ca2+ exchanger into artificial lipid vesicles consisting of either asolectin or phosphatidylserine, phosphatidylcholine, and cholesterol has little effect on temperature dependence of Na(+)-Ca2+ exchange velocity in any of the three species. We conclude that the lesser temperature sensitivity of the cardiac sarcolemmal Na(+)-Ca2+ exchanger of a poikilothermic species is at least partly an intrinsic property of the transport protein.
Bersohn
M M
MM
West Los Angeles Veterans Affairs Mecical Center, CA 90073.
Vemuri
R
R
Schuil
D W
DW
Weiss
R S
RS
Philipson
K D
KD
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D004285:Dogs; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D011817:Rabbits; D011892:Rana catesbeiana; D012508:Sarcolemma / Q000378:metabolism*; D019831:Sodium-Calcium Exchanger; D013045:Species Specificity; D013816:Thermodynamics
D002352:Carrier Proteins; D019831:Sodium-Calcium Exchanger; D002118:Calcium