Colforsin dapropate hydrochloride (NKH477) increased cellular contraction and maximum intracellular calcium concentration in isolated adult rat cardiomyocytes, associated with increased cAMP content.
Does colforsin dapropate hydrochloride increase cellular contraction and intracellular calcium concentration in isolated adult rat cardiomyocytes?
Colforsin dapropate hydrochloride exerts a positive inotropic effect in rat cardiomyocytes by increasing intracellular calcium and accelerating its kinetics via cAMP elevation.
The present study was undertaken to characterize the positive inotropic action of colforsin dapropate hydrochloride (NKH477), a novel water-soluble forskolin derivative, on isolated cardiomyocytes of adult rats. Simultaneous measurements of cellular contraction and intracellular calcium concentration (Ca 2+ i ) were carried out. The effects of isoprenaline and ouabain on these parameters were also determined for comparison. The contraction and maximum Ca 2+ i of NKH477-, isoprenaline-, or ouabain-treated cells were increased concentration dependently. Peak shortening of NKH477-treated cells was positively correlated with the shortening velocity and inversely with the time to peak shortening. Maximum, but not minimum, Ca 2+ i in NKH477-treated cells was correlated with the rate of increase in Ca 2+ i and inversely with the time to maximum Ca 2+ i . Similar results were obtained with isoprenaline. In contrast, ouabain increased both maximum and minimum Ca 2+ i . Treatment with either NKH477 or isoprenaline increased cellular cAMP content, but treatment with ouabain did not. These results suggest that the positive inotropic action of NKH477 is associated with an increase in Ca 2+ i and acceleration of its kinetics.Key words: adenylate cyclase, calcium transient, colforsin dapropate, isoprenaline, ouabain.
Miyake et al. (Thu,) reported a other. Colforsin dapropate hydrochloride (NKH477) vs. Isoprenaline and ouabain was evaluated on Cellular contraction and intracellular calcium concentration ([Ca 2+ ] i). Colforsin dapropate hydrochloride (NKH477) increased cellular contraction and maximum intracellular calcium concentration in isolated adult rat cardiomyocytes, associated with increased cAMP content.