Effect of dB-c-AMP and forskolin on the 45Ca influx, net Ca uptake and tension in rabbit aortic smooth muscle.
The effects of dibutyril-adenosine-3',5'-cyclic monophosphate (dB-c-AMP) and forskolin on aortic tension and 45Ca influx were measured. dB-c-AMP reduced both the rate of force development and the maximal tension achieved in solutions containing various K+ concentrations. Stimulated 45Ca influx was also reduced, however, to a lesser extent than was the tension. Forskolin showed more marked effects of a similar nature. Thus, both these agents which increase intracellular c-AMP caused a rightward shift in the curve expressing force (ordinate) as a function of Ca2+ influx (abscissa). Consequently, we found that dB-c-AMP stimulated more net Ca to be taken up by sarcoplasmic reticulum (SR) at the same influx rate. The conclusion that c-AMP produced these effects by stimulating Ca uptake into the superficial SR was supported by the finding that dB-c-AMP increased the amount of Ca taken up into a caffeine releasable fraction.
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D005576:Colforsin / Q000494:pharmacology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats
D002132:Calcium Radioisotopes; D005576:Colforsin; D003994:Bucladesine; D011433:Propranolol; D002118:Calcium; D010646:Phentolamine