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Abstract: The tonic lability of isolated segments of the human radial artery was studied isometrically. The mechanical shock to this artery produced by its separation prior to its subsequent use as an autologous arterial bypass graft for coronary arteries provokes a persistent spasm of its smooth muscle that lasts for at least 5 h. Its tonic lability could be preserved by incubation in the presence of 0.5 mM Verapamil, which blocks Ca2+ channels in the membranes of smooth muscle cells. A 5-h perfusion recovered more than 20% of the initial tone. Lability of the tone could also be preserved by a 1 μM solution of Aminazine, a well-known inhibitor of calmodulin, an intracellular Ca2+-binding protein. In this case, a 3-h perfusion caused a 40% decrease in the tone. Hence, during the pretreatment of the radial artery for its subsequent coronary bypass grafting, the inhibition of calmodulin can be efficacious in preventing intra-and postoperative complications that can be produced by the spasm of arterial grafts.

Changes in intracellular Ca2+homeostasis induced by 1 μM Amiodarone solution were studied with muscle strips isolated from the right atrial auricles of patients with ischemic heart disease (IHD). The intracellular Ca2+homeostasis was evaluated through the changes in contractility in the muscle strips caused by a 60-s discontinuation of their stimulation by electrical pulses. It was found that, in 30% of the IHD patients, the atrial myocardium displayed an abnormal contractility. Myocardium samples with normal contractility displayed two types of inotropic response to the resumption of electrical stimulation. The first type was associated with a 30% decrease in the parameters of the contraction–relaxation cycle, whereas, for the second type, this decrease was stronger (by 70% or more). An incubation of the muscle samples with the Amiodarone solution suppressed the abnormal contractility, did not affect the muscles with the first type of response, and significantly (p< 0.05) increased the inotropic response in the muscles with the second type of reaction to a short interruption in their electrical stimulation. As Amiodarone itself induces no direct positive inotropic effects, it was supposed that, in some cases of IHD, the presence of Amiodarone in the atrial myocardium is associated with an increased ability of the sarcoplasmic reticulum to retain calcium ions accumulated. This phenomenon may contribute to the suppression of abnormal activity of the atrial myocardium and strengthen the direct antiarrhythmic effect of Amiodarone.

1.A study has been made of the molecular characteristics of polypiperylenes obtained by polymerization, under various conditions, on catalysts containing various lanthanides.2.The molecular mass of the polymer varies with the time of polymerization, the concentration of the monomer (CM) and the organoaluminum (CAl) component of the catalyst, and the nature of the lanthanide and the solvent. Equations relating CM, CA1, and the molecular mass have been derived.3.The kinetic parameters for piperylene polymerization on lanthanide catalytic systems have been calculated, and it has been shown that the organoaluminum compound is the principal chain transfer agent.

A closed system of equations is derived for the energy flux, and the boundary conditions are given. The transport coefficients and other parameters are found from elementary gaskinetic considerations for a high concentration of the solid phase. As an example, the solution is found for the problem of an “adiabatic” Couette flow for a granulated medium.