Abstract
Summary
Rat hearts were perfused with 5.6, 16, or 55 mM K+ buffer for 10 min. IPR (3 × 10−8 M) was infused and hearts assayed for cAMP and phosphorylase activation while the perfusate was assayed for glycerol and αGP. Both 16 and 55 mM K+ buffer blocked contraction of the heart. With infusion of IPR spontaneous contractions occurred, a delayed elevation of cAMP was observed, and also a delayed release of glycerol and αGP into the perfusate was detected when compared to 5.6 mM K+ perfused hearts. Hearts perfused with 55 mM K+ buffer revealed no increase in cAMP and no increase in the perfusate of glycerol and αGP after IPR infusion. Phosphorylase was elevated in 5.6, 16 and 55 mM K+ perfused hearts.
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