Vol. 13, Issue 11 (2024)

Author(s):
Ismailova ShN, Omonturdiev SZ, Inomjanov DR, Abdullaev IZ, Abdullaev AA, Bogbekov AI, Abduazimova DSh, Gayibov UG and Aripov TF

Abstract:
The Na+/Ca²+ exchanger (NCX1) is critical for the regulation of contraction and relaxation in vascular smooth muscle cells, particularly in the rat aorta. Under standard conditions in Krebs physiological solution, the concentration of Na+ ions is typically maintained at 118 mM. However, when Na+ concentration is reduced to 25 mM or replaced with choline chloride, a marked contraction occurs, likely due to an increase in intracellular Ca²+ concentration facilitated by the Na+/Ca²+ exchange system. In these experiments, Na+ in the Krebs solution was replaced with choline chloride to investigate this response. After removing the endothelium, an initial contraction was induced in normal Krebs solution, followed by a wash and a 30-minute incubation in Krebs solution with 1.18 mM choline chloride replacing NaCl. This modification led to a progressively increasing contraction, hypothesized to result from Ca²+ ion entry through the Na+/Ca²+ exchanger. These findings underscore the role of Na+/Ca²+ exchange in smooth muscle cell contraction by illustrating how variations in Na+ concentration can influence Ca²+ influx, providing insights into cellular ion exchange mechanisms and their influence on vascular tone.