Effects of diltiazem on calcium concentrations in the cytosol and on force of contractions in porcine coronary arterial strips

Abstract

1 Using front-surface fluorometry with fura-2-loaded porcine coronary arterial strips, we simultaneously measured effects of a Ca2+ antagonist, diltiazem, on cytosolic Ca2+ concentrations ([Ca2+]

Relationship between cytosolic calcium concentration and force in the papaverine‐induced relaxation of medial strips of pig coronary artery

“…The Ca2l sensitivity of the contractile regulatory apparatus (i.e. the [Ca2J]i-force relationship) is modulated by agonists (Morgan & Morgan, 1984;Hirano et al, 1990), coupled to G-proteins (Nishimura et al, 1988).…”

Role of extracellular and intracellular sources of Ca2+ in sarafotoxin S6b‐induced contraction of strips of the rat aorta

“…When tissues were exposed to 10;EM H-7, the Ca2"-independent contraction induced by sarafotoxin after a 60 min exposure to Ca2"-free solution was inhibited by 83.6 ± 3.7% (n = 3). (Figure 7) was similar to the pCa-force relationship noted with skinned arterial fibres of various species and organs Saida & Nonomura, 1978;Kuriyama et al, 1982 (Rasmussen et al, 1987;Murphy, 1989 Hirano et al, 1990). In the present study, we used front-surface fluorometry of fura-2 loaded rat aortic strips to examine the roles of extracellular and intracellular Ca2" and of the [Ca2+]J-force relationship in contractions induced by sarafotoxin.…”

“…It has been reported that endothelin also evokes a Ca2l-independent, transient contraction in porcine coronary arterial strips (Kodama et al, 1989). The (Hirano et al, 1990). It was suggested (Schichtele et al, 1989) that diltiazem might have no direct effect on the Ca2"-sensitivity of contractile elements.…”

“…Front-surface fluorometry Fura-2 fluorescence was measured with a front-surface fluorometer specially designed for fura-2 fluorometry (CAM-OF-1), with the collaboration of Japan Spectroscopic Co., Tokyo, Japan (Hirano et al, 1990;Abe et al, 1990). In brief, strips were illuminated by guiding alternating (400 Hz) 340 nm and 380 nm, excitation light from a xenon light source through quartz optic fibres arranged in a circle (3 mm diameter).…”

“…Loading with fura-2 did not alter the time course of force development nor the maximum force attained. Contractions were measured with a force transducer (TB-612T, Nihon Koden, Tokyo, Japan) and results were expressed as a percentage of the maximal response elicited in 118 mM K4-containing solution (Hirano et al, 1990).…”