The measurement of drug-induced calcium changes in vascular smooth muscle using X-ray microanalysis of pyroantimonate precipitates.

A method is described for the X-ray microanalysis of calcium pyroantimonate precipitates in smooth muscle using an electron microscope. Stimulation of calcium influx through voltage-operated channels using KCl and blockade of this effect with nifedipine were used to validate the method. Significant changes in the calcium content of rat renal artery were detected when osmium tetroxide-pyroantimonate were used as fixatives, whereas addition of glutaraldehyde yielded unsatisfactory data. Some effects of hydralazine are also briefly described.