ATP-Dependent Calcium Transport in Rat Parotid Basolateral Membrane Vesicles: Modulation by Agents Which Elevate Cyclic AMP
Journal of Biological Chemistry
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.
Adenosine Triphosphate (ATP), parotid gland, rats, calcium, cyclic AMP, isoproterenol
Helman, J.; Kuyatt, Brian L.; Takuma, T.; Seligmann, B.; and Baum, B. J., "ATP-Dependent Calcium Transport in Rat Parotid Basolateral Membrane Vesicles: Modulation by Agents Which Elevate Cyclic AMP" (1986). Center for Teaching and Learning Publications. 14.