title: Effects of cAMP- and cGMP-dependent protein kinases, and calmodulin on Ca2+ uptake by highly purified sarcolemmal vesicles of vascular smooth muscle.
abstract: Sarcolemmal fractions of vascular smooth muscles were prepared from porcine thoracic aortae by differential and sucrose density gradient centrifugation. In these fractions, there was a high activity of 5'-nucleotidase, a putative marker enzyme of plasma membrane, and a low activity of rotenone insensitive NADH-cytochrome c reductase a marker of sarcoplasmic reticulum. In these fractions, the Ca2+ uptake was ATP-dependent. A low concentration of saponin which inhibited Ca2+ uptake by the plasma membrane but not by the sarcoplasmic reticulum, inhibited 65% of the Ca2+ uptake of this fraction. The Ca2+ uptake of this fraction was enhanced by cAMP- and cGMP-dependent protein kinases, and by calmodulin. The cAMP-dependent protein kinase enhanced the phosphorylation of 28 and 22 kDa proteins, while the cGMP-dependent protein kinase phosphorylated the 35 kDa protein. The phosphorylation of 100, 75, 65, 41 and 22 kDa proteins was enhanced by Ca2+ and calmodulin. These results indicate that cAMP- and cGMP-dependent protein kinases as well as calmodulin play important roles in Ca2+ transport in the sarcolemma, and that the phosphorylated proteins may be associated with an enhancement of Ca2+ transport in the sarcolemma.
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D007700:Kinetics; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D012508:Sarcolemma / Q000378:metabolism*; D013552:Swine
chemical_list: D002147:Calmodulin; D000242:Cyclic AMP; D011494:Protein Kinases; D006152:Cyclic GMP; D002118:Calcium