ATP-dependent calcium transport in rat parotid basolateral membrane vesicles. Modulation by agents which elevate cyclic AMP.
ATP-dependent Ca2+ transport was studied in basolateral membrane vesicles prepared from rat parotid gland slices incubated without or with agents which increase cyclic AMP. Isoproterenol (10(-5) M), forskolin (2 X 10(-6) M) and 8-bromocyclic AMP (2 X 10(-3) M) all increased ATP-dependent 45Ca2+ uptake 1.5- to 3-fold. The effect of isoproterenol was concentration-dependent and blocked by the beta-adrenergic antagonist propranolol. Enhanced uptake did not appear an artifact of vesicle preparation as apparent vesicle sidedness, 45Ca2+ efflux rates, specific activity of marker enzymes and equilibrium Ca2+ content were identical in vesicle preparations from control and 8-bromocyclic AMP-treated slices. Kinetic studies showed the ATP-dependent Ca2+ transport system in vesicles from 8-bromocyclic AMP-treated slices displayed a approximately 50% increase in Vmax and in Km Ca2+, compared to controls. The data suggest that physiological secretory stimuli to rat parotid acinar cells, which involve cyclic AMP, result in a readjustment of the basolateral membrane ATP-dependent Ca2+ pump.
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D010306:Parotid Gland / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D002132:Calcium Radioisotopes; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D007545:Isoproterenol; D002118:Calcium