As there may be some differences in the mechanism of the initiation and progression of the atherosclerosis between each organ artery, we studied effects of various vasoactive drugs on the cultured smooth muscle cells (c-SMC) obtained from the aorta, coronary and renal arteries of swine. Contractive effects by methacholine, noradrenaline and serotonin were examined on ultrastructural basis. The obtained results were as follows.
1) Each three kind of drugs made all c-SMC obtained from each artery contracted.
2) After contraction, there were a reduction in cell volume, and globular cytoplasmic projections, which could be divided into three categories by size.
3) Contraction activity of c-SMC was different in its intensity between each organ artery. By methacholine, the renal arteries were the most and followed by the coronary arteries in contraction intensity, and the aorta was weakest. By noradrenaline, the coronary arteries was most intensive and followed by the renal arteries and the aorta was weakest. By serotonin, the coronary arteries were similar to the renal arteries and the aorta was weaker than other two.
4) It was suggested that large-sized globular projections were correlated with perinuclear vacuoles occurred during vascular spasm in the renal arteries, reported previously by Takeuchi.