抄録
Cardiovascular (CV) reactivity to norepinephrine (NE) after cocainization, and to methoxamine was determined in spontaneously hypertensive rats (SHR), and in rats made hypertensive by clipping the renal artery and contralateral nephrectomy, or by the administration of deoxycorticosterone and salt. Cocaine inhibits the uptake of NE at the nerve terminals. Methoxamine is a sympathomimetic amine, not taken up by the nerve endings. The full dose-response curves were obtained without anesthesia after pithing, decerebration, and vagotomy. CV reactivity to NE was essentially unchanged after cocainization in the 3 types of hypertension. Reactivity to methoxamine was also unchanged in hypertension. The results indicate that neither differences in the mechanism of uptake nor sensitivity of the receptor sites is responsible for the elevated blood pressure (BP) in these types of hypertension. NE must be available in a larger amount at the receptor sites in the CV system to maintain the higher BP.
