K(+)-channel openers: new antihypertensive drugs?

K(+)-channel openers are a new class of drugs. They interact in a not yet identified fashion with a not yet identified population of K+ channels resulting in an increase in K+ conductance of the surface membrane. K(+)-channel openers have a high affinity for K+ channels of smooth muscle and distinctly less for cardiac or neuronal K+ channels. The cellular effects of K(+)-channel openers in smooth muscle include hyperpolarization, decrease in membrane resistance, inhibition of propagation of excitation, suppression of spontaneous electrical and mechanical activity and inhibition of agonist-induced contraction. The pharmacodynamic profile of K(+)-channel openers is reminiscent of typical vasodilators with decreases in total peripheral resistance and blood pressure and reflex increases in heart rate and cardiac output. While there is no doubt that K(+)-channel openers are effective antihypertensive agents, it is too early, at present, to define their future role in cardiovascular therapy. A satisfactory treatment of hypertension by these drugs may require the addition of diuretics and/or beta-blockers. Other potential clinical indications of K(+)-channel openers include coronary heart disease and asthma.