Cyclic AMP but not phosphorylation of phospholamban contributes to the slow inotropic response to stretch in ferret papillary muscle
- 23 March 1999
- journal article
- research article
- Published by Springer Nature in Pflügers Archiv - European Journal of Physiology
- Vol. 437 (5) , 780-782
- https://doi.org/10.1007/s004240050846
Abstract
CAMP has been suggested to mediate the increased intracellular Ca2+ transient and contraction seen during the slow response to stretch in cardiac muscle. We measured cAMP in ferret papillary muscles stretched from 80–85% to 98% of their length at which maximum active tension is produced (Lmax) for 15 min. cAMP was significantly (P2+ uptake by phosphorylation of phospholamban, we found no significant effect of stretch on phosphorylation of phospholamban at either Ser16 or Thr17. Further support for the hypothesis that cAMP is a mediator of the slow response was obtained by exposure of some muscles to the cell-permeable cAMP antagonist 8-bromo, adenosine 3′,5′-cyclic monophosphorothioate, Rp isomer (Rp-8-Br-cAMPS, (2.5–10 µM). The slow response was reduced by 30% (P<0.05) in the presence of this antagonist. Our results not only provide evidence for the mediation of the slow response to stretch by cAMP, they also suggest that cAMP may rise in an intracellular compartment inaccessible to the SR.Keywords
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