Sarcolemmal vesicles were isolated from porcine small intestine, were carried out experiments of Na, K-ATPase activity determination and ^(45)ca-uptake. Also these vesicles were loaded with 160mM KCI and 0.6mM ^(45)CaCl₂, and incubated in the solution contained KCI and EGTA, to induce calcium efflux for a given period.
The obtained results were as follows:
1. Na, K-ATPase activity of this membrane was about 4.5 ㎛ol Pi/mg protein/hr, and with the treatment of SDS (0.2mg/ml), this activity was increased about 1307.
2.^(45)Ca-uptake in the presence of ATP (1.2mM) was markedly increased as compared to that in the absence of ATP (about 42-50%).
3. ^(45)Ca-efflux in the alkaline solution (pH 7.6 or 8.5) was markedly increased as compared to that in the solution of pH 7.0.
4. With the addition of ATP (1.2mM), ^(45)Ca-efflux was decreased significantly.
5. ^(45)Ca-efflux in the various pH solution (pH 7.0, 7.6 or 8.5) was not influenced by the treatment of diltiazem, but that in the presence of ATP, was inhibited significantly with the treatment of diltiazem (10^(-5)M) (p.<0.05).
From the shove results, it was suggested that calcium channel of sarcolemma which was isolated from porcine small intestine, could be regulated with diltiazem by the phosphorylation of sarcolemma, but not influenced by alkalosis.
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