[Contractile activity and sensitivity of smooth muscle cells of the small intestine to agonists in acute ileus]. / Sokratitel'naia aktivnost' i chuvstvitel'nost' k agonistam gladkomyshechnykh kletok tonkoi kishki pri ostroi neprokhodimosti kishechnika.

The impact of acute ileus on the contractility and sensitivity of small intestinal smooth muscle cells to acetylcholine and histamine, as well as possible recovery of smooth muscle cells after removal of 3-hour acute ileus were studied. The contractility of small intestinal smooth muscle cells and their sensitivity to the agonists decreased in proportion to the duration of acute ileus only in the strangulated portion of the bowel. Removal of 3-hour acute ileus resulted in a stepwise recovery of the contractility and sensitivity of small intestinal smooth muscle cells to the agonists in the adducting, strangulated, and abducting portions. It is suggested that in acute ileus, the structure of smooth muscle receptors undergo modification due to tissue homeostatic changes or to the direct action of cell destruction products on receptors.

[Activation of the fast calcium input in the denervated smooth muscle of the cat nictitating membrane]. / Aktivatsiia bystrogo kal'tsievogo vkhoda v denervirovannoi gladkoi myshtse migatel'noi pereponki koshki.

The excitation and contraction features of innervated and sympathetically denervated smooth muscle strips from cat's nictitating membrane have been studied by single sucrose gap arrangement. Increasing of smooth muscle cells sensitivity to drugs were accompanied by elevation of membrane response and the ability to generation of action potentials. Action potentials have been induced by agonists or high potassium concentration in external solution and spontaneously. In innervated muscle action potentials have been evoked as a result of depolarization by high potassium concentration of TEA blockade of potassium conductance. Induced and spontaneously generated action potentials were blocked by organic and inorganic antagonists of potential dependent Ca++ channels. In Ca-free solution action potentials were absent but might be supported by Ba++. Decrease of Na+ had no effect on smooth muscle excitability. It is supposed that activation of potential depended Ca++ channels in smooth muscle cells with pharmaco-mechanical coupling are under influence of sympathetic nerves.

[The electrical and contractile activity of denervated smooth muscle]. / Elektricheskaia i sokratitel'naia aktivnost' denervirovannoi gladkoi myshtsy.

The effect of norepinephrine, histamine, serotonin and potassium chloride on electrogenesis and contraction was studied on innervated and denervated smooth muscles of cat's nictitating membrane. Denervated smooth muscles generate slow depolarizing potentials with the APs corresponding to tonic and phasic contractions, resp. Tonic contractions occur with no considerable change fo the MP in innervated muscles, phasic contractions being absent. Spontaneous generation of the APs is only possible in denervated muscles. Pharmacomechanical type of coupling between excitation and contraction seems to be characteristic of innervated smooth muscles, whereas electromechanical type is characteristic of denervated muscles. The denervation seems to result not only in the change of cells' sensitivity to transmitters but in the abnormality of coupling processes between excitation and contraction as well.