[Research of cytoskeleton-dependent mechanisms of contractile activity regulation in the smooth muscles].

Influence of modulation of cytoskeleton by colchicine, vinblastine and cytochalasine B on contractile reactions of smooth muscles has been investigated by mechanographical method, by the methods of the double sucrose gup junction. Ratio F/G-actin in smooth muscle cells defined a method of a fluorescent microscopy. Microfilaments in a greater degree than microtubule are involved in regulation of reductions caused by hyperpotassic-induced reductions of membrane of smooth muscle segments of the rat aorta and generation of action potentials and reductions smooth muscle cells from guinea pig urethra. Reductions of vascular segments of aorta in rats caused by a hyperosmotic solution depend on condition of microfilaments and microtubules, whereas reductions in isoosmotic striction cells depend on condition of microfilaments. The last are involved in mechanisms of phenylephrine influence on mechanical strain of vascular segments of the rat aorta. Contrary to that, microtubules are involved in stimulation by phenylephrine electric and contractile activity the smooth muscle cells guinea pig urethra. Oppressiof contractile activity of smooth muscle segments of the rat aorta is cAMP-mediated and depends on condition of microfilaments of cytoskeleton, while action potentials and reductions smooth muscle cells of a ureter depend on condition of microtubules.

[Na+,K+,2Cl(-)-cotransport and chloride permeability of the cell membrane in mezaton and histamine regulation of electrical and contractile activity in smooth muscle cells from the guinea pig ureter].

Influence of Na+,K+,2Cl(-)-cotransport and chloride permeability of the cell membrane on electrically-induced action potential and contraction of smooth muscle cells from guinea pig ureter was examined with the methods of the double sucrose gap junction. Mesatone (10 microM) and histamine (10 microM) induced prolongation of the action potential and elevation of smooth muscle cell contraction, whereas hyperosmic medium (+150 mM sucrose), and recovery of solution osmolality in hyposmic condition (70 mM NaCl) after a single contraction. Inhibitor Na+,K+,2Cl(-)-cotransport bumetanide (10 microM) and chloride permeability blockers niflumic acid (10-100 microM) and SITS (10-500 microM) attenuated stimulating effects of mesatone, histamine and hyperosmic medium. In opposite to adenylate cyclase activation with forskolin (1 microM), guanylate cyclase activation with sodium nitroprusside (SN, 100 microM) decreased both inhibitory action of bumetanide, niflumic acid and activating effects of mesatone, histamine on action potential and elevation contraction of smooth muscle cells. Influence of forskolin rather and not SN on AP and SMC C was inhibited with tetraethylammonium (5 mM). These results suggest that influence of Na+,K+,2Cl(-)-cotransport on electrical and contractil properties of ureter smooth muscle cells is mediated by stimulation of Ca(2+)-activated chloride permeability of the cell membrane and modulated by intracellular cGMP, but not triggered by Ca2+ release from sarcoplasmic reticulum.

[Myogenic effects of cyclic guanosine monophosphate in smooth muscle cells. Role of protein kinase C]. / Miogennye éffekty tsiklicheskogo guanozinmonofosfata v gladkomyshechnykh kletkakh. Rol' proteinkinazy C.

Heterogeneity of the cGMP-dependent contractility effects of the smooth cells (SMC) was shown in guinea pig ureter by the methods of the double sucrose gap junction. Sodium nitroprusside (SN, 0.1-100 microM) relaxed the high-K+ depolarisationprecontracted SMC but strengthened the SMC constriction triggered by electrical stimulation. In taenia coli, SN or nitroglycerin in the same concentration ranges depressed the electrical or mechanical activity of the SMC and relaxed the SMC, precontracted by depolarization in high-K+ medium. The inhibitor of the phosphodiesterases vinpocetine (1 microM) contributed to the activating effect of SN; the inhibitor of the soluble guanilatcyclase Methilen Blue (10 microM) depressed it. Histamine and mesotone (1-10 microM) increased the action potential and constriction of the SMC triggered by electrical stimulation but decreased the effect of SN. The activator of the protein kinase C (PK-C) phorbol miristoyl-13-acetyl (0.5 microM) changed direction of the SN effects inhibiting both the parameters of an action potential and of the SMC constriction. The pre-treatment with the inhibitor of PK-C calphostin C (0.1 microM) additionally depressed the effects of SN, increasing SMC constriction, especially in the presence of histamine and mesatone. We suggest that c-GMP depressed activity of the PK-C by independent mechanisms operating in SMC.

[Regulation of smooth muscles of the vascular wall in the rabbit pulmonary artery]. / Osobennosti reguliatsii gladkikh myshts sosudistoi stenki legochnoi arterii krolika.

The cholinergic, histaminergic and adrenergic features of regulation of the small muscles contractile activity in a vascular wall of a pulmonary artery in rabbits and involvement of an endothelium in these processes, were investigated. The cholinergic release phenomenon of small muscles of the rabbit pulmonary artery has a two-component character of dose dependence. The low-threshold components of Pilocarpinum relaxing effect has an endothelium-dependent nature. The important feature of histaminergic regulation of contractile activity of segments involves a direct contractile effect of histamine that is not inherent. The endothelium renders a suppressing effect on histaminergic contraction of small muscles of the rabbit pulmonary artery. A basic feature of adrenergic regulation of the pulmonary artery involves registered-beta-adrenergic contractile effects in small muscles of a vascular wall. The activation of the cAMP-dependent signal system in small muscles of a pulmonary artery is capable of rendering a contractile effect. The detected features of a regulation in the small circle can have an essential clinical-physiological value.