Sympathetic and humoral vasoconstrictor responses in deoxycorticosterone hypertension

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Abstract
Vasoconstriction was induced by lumbar sympathetic chain stimulation and intra arterial injection of drugs in the perfused hindquarters of rats rendered hypertensive by deoxycorticosterone (DOC) and salt administration. Experiments were conducted 6,12, and 18 wk. after initiation of DOC treatment. Pressure flow determinations indicated that the vascular resistence of the hindquarters was significantly higher in hypertensive animals at all 3 periods. Vasoconstrictor responses to sympathetic stimulation at frequencies of 1.25-5 pulses/sec were similar in control and treated groups, whereas effects of higher frequencies (10 and 20 pulses/sec) tended to be slightly exaggerated in hypertensive rats. On the other hand, intraarterial injection of noreplnephrine and anglotensln consistently resulted in greater vasoconstriction in treated animals. These results suggest that the elevated vascular resistance of the hindquarters of hypertensive rats is probably not the result of increased reactivity to nervous impulses.