title: Cation-induced aggregation of membrane vesicles isolated from vascular smooth muscle.
abstract: Cations stimulated aortic muscle membrane aggregation with increasing potency according to their effective charge, e.g., K+ less than Mg2+ less than La3+, and the stimulation is reciprocally related to the apparent affinity for these cations. Divalent metal ion-induced membrane aggregation showed a dependence on the ionic radius, being optimal for Cd2+. Polyvalent cation-induced membrane aggregation was reversibly suppressed by high ionic strength as well as by metal ion chelators, irreversibly inhibited by the cross-linking agent glutaraldehyde, and enhanced by increasing concentrations of ethanol and increased temperature of the medium. When the pH is lowered below 6.0, membrane aggregation progressively increased with a concomitant decrease in cation-induced aggregation. The patterns of aggregation of microsomal membranes and further purified plasma membranes were almost identical whereas the aggregation of the heterogeneous mitochondrial membrane-enriched fraction was distinctly different in the initial rate of aggregation, its pH dependence, and metal ion concentration dependence. Our results indicate that cation-induced membrane aggregation can also be used to isolate a plasma membrane-enriched fraction from vascular smooth muscle.
mesh_terms: D000818:Animals; D002412:Cations; D002462:Cell Membrane / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D004285:Dogs; D000431:Ethanol / Q000494:pharmacology; D005976:Glutaral / Q000494:pharmacology; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000187:drug effects; D008561:Membrane Fusion / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000648:ultrastructure; D009994:Osmolar Concentration; D011522:Protons; D013696:Temperature
chemical_list: D002412:Cations; D002614:Chelating Agents; D011522:Protons; D000431:Ethanol; D005976:Glutaral