[Clinical and experimental study of clofelin pharmacodynamics].

Hemodynamic mechanisms of clophelin hypotensive effect were studied in 122 patients with arterial hypertension. In most cases, antihypertensive clophelin therapy did not affect the nature or magnitude of orthostatic and stress-induced hemodynamic shifts. The fact that the fall in perfusion BP was not accompanied with a resting, orthostatic or stress-induced impairment of renal function was a particularly valuable aspect of clophelin treatment.

[Role of transmembrane ion currents in the mechanism of action of beta-adrenoblockers].

The effects of propranolol, oxprenolol, pindolol, labetalol, and atenolol on the isoproterenol-stimulated slow calcium current as well as on spontaneous slow calcium and fast sodium currents were studied in frog trabeculae by the double sucrose bridge technique. Administration of beta-adrenoblockers in low doses (10(-7)-10(-6)M) antagonized the stimulatory effect of isoproterenol on the slow calcium current (pindolol greater than oxprenolol greater than or equal to propranolol = labetalol greater than atenolol). When administered in high doses (2 X 10(-6)-10(-4)M) the beta-adrenoblockers reduced the slow calcium current.