[Effect of compound 48/80 on masseter muscle sarcoplasmic reticulum calcium transport system].

To define the role of calmodulin in Ca2+ fluxes behavior of canine masseter muscle sarcoplasmic reticulum (SR) vesicles, the effect of condensation product of N-methyl-p-methoxy-phenethylamine with formaldehyde (compound 48/80), a selective and powerful inhibitor of calmodulin-regulated function, on Ca(2+)-ATPase activity, oxalate-supported Ca2+ uptake velocity, and on interaction with Ca2+ permeability and Ca2+ loading at steady-state were evaluated. Compound 48/80, at concentrations of 10 to 100 micrograms/ml, reduced oxalate-supported Ca2+ uptake velocity without affecting Ca(2+)-ATPase activity. In the presence of 10 micrograms/ml compound 48/80, there was a shift of pH- or temperature-response curve of oxalate-supported Ca2+ uptake velocity, but not of Ca(2+)-ATPase activity, down.

The effect of oxygen free radicals on calcium permeability and calcium loading at steady state in cardiac sarcoplasmic reticulum.

It has been proposed that oxygen free radical production is an important mediator of the myocardial dysfunction during the course of acute ischemia. We tested this hypothesis by characterizing the pathway of calcium efflux across sarcoplasmic reticulum (SR) membranes affected by oxygen free radicals. The effect of oxygen free radicals on the steady state calcium load, calcium permeability, and Ca,Mg-ATPase activity of isolated canine cardiac SR vesicles was investigated at pH 7.

Characterization of the effect of pH on the excitation-contraction coupling system of canine masseter muscle.

The effect of pH on the excitation-contraction coupling system of canine masseter muscle was studied by evaluating the functional integrity of the sarcoplasmic reticulum (SR) and myofibrils. Increasing proton concentration (pH 7.0-5.

Free radicals-induced changes in mesenteric microvascular dimensions in the anesthetized cat.

Effect of free radicals on microvascular dimensions was studied in anesthetized cat intestinal mesentery. Generation of free radicals by xanthine oxidase, acting on endogenous substrates (e.g.