Myocardial contractile actions of endothelin-1 in rat and rabbit papillary muscles. Role of endocardial endothelium.

摘要: The actions of endothelin on the contractile and twitch configuration characteristics rat rabbit papillary muscles were evaluated before after endocardial endothelium removal. In muscles, produced a dose-dependent (10(-11) to 10(-7) M) increase in tension (T) (from 2.7 +/- 0.2 8.9 0.7 g/mm2, p less than 0.01), dT/dt, Vmax 1.14 0.03 3.0 0.13 Lmax/sec, decrease time peak 251 9 216 7 msec, 0.05), an half relaxation 168 293 14 0.01). Increasing calcium concentration bath from 1.25 15 mM greatly attenuated these changes. presence propranolol (10(-5) M), increased all indexes contractility but lesser extent (T = 2.6 0.3 6.5 0.01; 1.16 0.10 2.06 Myocardial catecholamine depletion with reserpine had effects similar those propranolol. myocardial phenylephrine (10(-4) strong stimulator phosphatidylinositol pathway moderate beta-adrenergic stimulator. modified manner by M). nicardipine (3 X decreased absolute caused did not alter percent change or shift dose-response curve endothelin. studied at physiological concentrations (Ca2+ mM) marked high mM). Removing endothelial layer changes shifted left markedly altered characteristics. Thus, it would appear that increases modifies configuration. It does so more lower rather higher extracellular species, such as rabbit, responds interventions intracellular calcium.(ABSTRACT TRUNCATED AT 400 WORDS)