Intracellular free Ca2+ and vasoconstriction determined simultaneously in the perfused rat tail artery.

To measure, simultaneously, intracellular free Ca2+ ([Ca2+]i) and vasoconstriction in a perfused vessel, we used the fluorescent Ca2+ indicator fura 2 with a dual-wavelength excitation method. One-centimeter-long segments of the caudal artery were dissected from 12-mo-old male Wistar rats. The endothelium was removed by gentle rubbing. The artery was mounted in a specially constructed spectrofluorometer cuvette, perfused with oxygenated physiological saline solution at 37 degrees C, and loaded by perfusion with fura 2 acetoxymethyl ester (5 microM) over a 90-min period. This paper is a description of the technique and the experiments that validate it as a useful method for examining Ca(2+)-related vascular reactivity in an intact perfused vessel.