Response of isolated adult canine cardiac myocytes to prolonged hypoxia and reoxygenation
Hohl, C.M.; Altschuld, R.A.
American Journal of Physiology 260(3 Pt 1): C383-C391
1991
ISSN/ISBN: 0002-9513 PMID: 2003568 Document Number: 382678
Isolated adult canine ventricular myocytes incubated in the absence of glucose with the respiratory inhibitor rotenone retained 67% of ATP (control, 26.0 .+-. 0.9 nmol/mg protein) during 3-h incubation, yet phosphocreatine fell to 23% of initial content. Lactate production proceeded at a constant rate of 5 nmol .cntdot. mg-1 .cntdot. min-1 in rotenone-treated glucose-free myocytes. A 36% decline in rod-shaped cells and an increase in percent 22Na permeation from 37% in aerobic cells (.apprx.13 mM intracellular sodium) to 68% in rotenone-treated glucose-free myocytes paralleled the loss of ATP. Total exchangeable calcium was maintained at control aerobic levels. Exposure of canine cells to 3-h hypoxia in the absence of glucose followed by 5-min reoxygenation resulted in a 73% decrease in ATP, a rise in calcium from 3.3 .+-. 0.2 to 6.6 .+-. 1.6 nmol/mg, and an increase in 22Na permeation to 111%. Under these conditions the number of rod-shaped myocytes declined by 77% with corresponding increases in viable contracted and hypercontracted myocytes. The response of canine myocytes to severe hypoxia and reaeration contrasts greatly to earlier studies using adult rat cardiac myocytes [see Hohl et al. Am. J. Physiol. 242 (Heart Circ. Physiol. 11): H1022-H1030, 1982]. Species differences with respect to basal metabolism, rates of ATP production and degradation, and regulation of cation movements are most likely responsible for the observed differences.