The report deals with the effect of
ischemia and reperfusion on purified sarcolemma obtained from canine myocardium of perfused supported heart preparations. Perfusion was carried out with a perfluorochemical (FC-43).
Ischemia was produced by intermittent total clamping of inflow and outflow followed by release until the decrease in dP/dtmax had become stabile. Purity of sarcolemmal vesicles was ascertained with marker
enzymes:
succinate cytochrome c reductase (for mitochondria), K+-stimulated p-
nitrophenylphosphate (K+-pNPPase), (Na+/K+)
ATPase and
adenylate cyclase (for SL). In addition Na+/Ca2+-exchange characteristics for SL were determined. Sidedness of vesicles was ascertained by means of
adenylate cyclase activity using sarcolemmal preparations treated and untreated with
alamethicin. Emphasis was placed on
ATP-dependent Ca2+ uptake, phosphorylation of sarcolemmal vesicles and yield of SL
proteins.
Ischemia and reperfusion resulted in a significant reduction in
adenylate cyclase activity. This decline was significant following
ischemia and reperfusion. The yield of
protein recovered from SL vesicles from ischemic-reperfused heart preparations was also significantly decreased. Both initial rate of
ATP-dependent Ca2+ uptake and maximal Ca2+ uptake fell significantly following
ischemia and reperfusion. The initial rate of phosphorylation also dropped significantly. These disturbances in SL Ca2+ transport following
ischemia and reperfusion are probably a part of the general deficit in Ca2+ translocation.