Ionic selectivity of chloride ion symport in mechanisms controlling resting potential and osmotic homeostasis in earthworm somatic muscle cells

Abstract

Replacement of Cl- for Br- in bathing solution did not reduce resting potential and had no effect on modulation of transmembrane potential in hyper-and hypoosmotic solutions. Under these conditions, baclofen, an agonist of GABAergic B-type receptors, failed to activate Na+/K+-pump in earthworm somatic muscle cells. It was hypothesized that the contribution of Cl- symport to osmotic homeostasis is not highly selective in respect to replacement of Cl- to Br- ions, whereas in case of activation of electrogenic ion pumps, this replacement is equivalent to removal of Cl- ions from the bathing solution. [PUBLICATION ABSTRACT]