Chronic experimental hypertension in dogs after constriction of brachicephalic and left subclavian arteries.

• Chronic hypertension of moderate to marked severity has been produced in dogs by bilateral carotid sinus area constriction with specially devised plastic clamps.' 3 Three possible mechanisms have been proposed to explain this type of experimental hypertension: (a) an alteration in cerebral hemodynamics, presumably leading to the liberation of an increase in total peripheral resistance;'' (b) a chronic absence of impulse traffic over the sinus nerves caused by the placement of the plastic clamps over the carotid sinus area;' (c) a combination of the above proposals. In dogs, adequate constriction of the common carotid arteries above the thyroid arteries leads to immediate development of a severe hypertension° which persists for two to three weeks, followed by return of blood pressure to normotensive levels. The most likely explanation for this course of events is the rapid development of collateral circulation with adequate retrograde flow into the sinus areas.'' In the studies to be reported, an effort was made to avoid this problem of collateral circulation by simultaneously constricting the brachiocephalic and left subclaviau arteries instead of the common carotids. Studies are presented which show: (a) that chronic hypertension can be produced in dogs by simultaneous constriction of the brachiocephalic and left subclavian arteries; (b) the pattern and general nature of the hyperten-