Mechanisms of regulation electric and contractile activity smooth muscle cells: the role of cytoskeleton

The influence of modulation of cytoskeleton by colchicine, vinblastine, cytochalasine B and docetaxel on contractile reactions of smooth muscle cells caused by electric stimulus, depolarization, phenylephrine has been investigated by the mechanographical method, by the methods of the double sucrose gup junction. It is established, that induced by a isoosmotic hyperpotassium solution of reduction of smooth muscle of the rat’s aorta, and also caused depolarization stimulus potentials of action and reductions smooth muscle cells from guinea pig urethra, depend more on the condition of microfilaments cytoskeleton than on microtubules. The reduction of smooth muscles cells of an aorta of the rat, caused by isoosmotic striction, is suppressed under the destruction microfilaments whereas the reduction in a hyperosmotic solution depends on a condition of both microfilaments, and microtubules. Cytoskeleton’s microfilaments of aorta’s smooth muscles and microtubules of smooth muscles of cells ureter are involved in mechanisms of action phenylephrine’s action on contractile activity of smooth muscle cells of an aorta and ureter.

The role of cytoskeleton in the regulation of contractile activity in smooth muscle cells from aorta of rats

Influence of cytoskeleton modulation by Colchicine and Cytochalasine B on contractile reactions of smooth muscle segments of rat's aorta caused by physiologically active substances, the membrane's depolarization and cells' striction was investigated by mechanographical method. Microtubules and actinic elements of the cytoskeleton were established to participate in the development of hyper-potassic and phenylephrine -induced contractions as well as in the smooth muscle relaxation induced by cAMP. Cytochalasine B suppresses both kinds of aortic smooth muscle contractions more effectively than Colchicine. Contractile reactions at isoosmotic striction are suppressed only by Cytochalasine. Efficacy of cAMP signal system operating depends on actinic cyto-skeleton integrity.

Cholinoceptor Activation Subserving the Effects of Interferon Gamma on the Contractility of Rat Ileum

Recombinant rat interferon γ stimulated the contractility of isolated rat ileum at doses of 4–12 units/ml. Muscarinic cholinoceptors were involved, as treatment of the tissue with atropine prevented the contractile response of the ileum. Furthermore, interferon γ increased the affinity of carbachol for the cholinoceptors and did not change its maximum effect. Neurogenic pathways were also involved since pretreatment of ileum with hexamethonium, hemicholinium or tetrodotoxin impaired the contractile effect of interferon γ. In contrast to the action of exogenous carbachol, the effects of interferon γ are indirect. They appear to involve a G protein regulating phosphoinositide turnover and cytoskeletal structures since they could not be induced in ileum strips that were pretreated with pertussis toxin, phospholipase C inhibitors (2-nitro-carboxyphenyl,NN-diphenyl carbamate and neomycin), cytochalasine B or colchicine.