title: Ca2+ handling properties of microsomal subfractions of rat vas deferens smooth muscle.
abstract: The rat vas deferens smooth muscle microsomes on isopycnic centrifugation gave two fractions, namely F2 (15-30% sucrose) and F3 (30-40% sucrose), with comparable ATP-dependent azide-insensitive Ca2+-uptake capacities, although these fractions differed from each other in various enzyme marker activities. The fractions F2 and F3 also show similar pH profiles for the ATP-independent and ATP-dependent Ca2+ uptake, and similar ionized Ca2+-concentration dependence for the ATP-dependent Ca2+ uptake. However, the fractions F2 and F3 differ from each other in that: (a) F3 shows higher permeability to Ca2+, and (b) F3 shows higher stimulation of the ATP-dependent Ca2+ uptake by oxalate. The F3 fraction can also be used to obtain membrane vesicles loaded with Ca2+ oxalate in the presence of ATP. However, the yield of the Ca2+ oxalate enriched fraction is too low to permit their further characterization.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002129:Calcium Oxalate / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D008861:Microsomes / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism; D010070:Oxalates / Q000378:metabolism; D019815:Oxalic Acid; D051381:Rats; D014649:Vas Deferens / Q000378:metabolism*
chemical_list: D010070:Oxalates; D002129:Calcium Oxalate; D000255:Adenosine Triphosphate; D019815:Oxalic Acid; D002118:Calcium