Danylovych Y. Biochemical patterns of nitrogen and oxygen active metabolites action on Ca ion transport in uterus smooth muscle

The research is devoted to the elucidation of biochemical and physico-chemical mechanisms of nitrogen and oxygen active metabolites action on myometrium Ca2+-transport systems. It was established that nitric oxide stimulates dihydropyridine-sensitive Ca2+ transport in myocytes. This leads to the activation of Ca2+-dependent K+-channels and plasmalemma hyperpolarization. NO-dependent activation of passive H+-transport from myocytes and cGMP-mediated stimulation of Na+,K+-ATPase promotes the growth of cell transmembrane potential. Nitric oxide enhances the energy-dependent accumulation of Ca2+, which comes in cell from the extracellular environment, on sarcoplasmic reticulum and mitochondria. At the same time, NO inhibits pool-operated transport of Ca2+ in myocytes. Nitrogen active metabolites inhibits electro(pharmaco)-mechanical coupling in the myometrium, decreasing Ca2+-induced Ca2+ release from the sarcoplasmic reticulum and reducing Ca2+ binding ability to calmodulin. Hydrogen peroxide is able to influence the Ca2+-homeostasis of myometrium cells by the ways partly similar to nitric oxide. A conceptual model of the biochemical mechanisms of nitrogen active metabolites action in the myometrium is proposed.