1. Na(+)-Ca++ exchange mechanism in smooth muscle of the ureter.
- Author
-
Kazarian KV, Hovhannissian HS, and Hakobian RR
- Subjects
- Action Potentials, Animals, Electric Stimulation, Guinea Pigs, Homeostasis, In Vitro Techniques, Intracellular Fluid metabolism, Ion Transport, Calcium metabolism, Muscle, Smooth metabolism, Sodium metabolism, Ureter metabolism
- Abstract
The participation of Na+ in regulation of intracellular Ca++ content and in formation of spontaneous action potentials of guinea-pig ureter was studied. It was shown that the fast decrease of intracellular Ca++ in the Ca(++)-loaded muscles was accompanied by enhancement of Na+ content in the cells. The concentration gradient of Na+ was found to define the effectiveness of Ca(++)-extrusion from Ca(++)-loaded cells. The decrease of intracellular Ca++ showed a sigmoidal dependence on Na+ content in the medium. A correlation was established between the concentration gradient of Na+ and the formation of action potential plateau of ureter smooth muscle cells. The duration of action potential plateau decreased in accordance with Ca++ efflux and Na+ influx. The results confirmed the participation of Na(+)-Ca++ exchange mechanism in support of Ca++ cellular homeostasis as well as in the generation of action potentials of guinea-pig ureter.
- Published
- 1994