The role of the sympathetic nervous system in 2-kidney DOCA-hypertensive Yucatan miniature swine.

To assess the mechanism responsible for maintaining the elevated arterial pressure in 2-kidney DOCA treated Yucatan miniature swine, cardiovascular parameters and the responses to hexamethonium bromide (HMB) were evaluated in normal and DOCA treated animals. Using chronically instrumented conscious animals, measurements of mean arterial pressure (MAP), cardiac output (CO), and calculated total peripheral resistance (TPR) revealed that with DOCA hypertension MAP was increased 50-60 mmHg above controls. This increased pressure was due to an increase in TPR with CO remaining normal. HMB normalized the MAP of the DOCA animals via a selective lowering of TPR to a value similar to that of the controls. In DOCA hypertensive animals these functional changes, due to increased peripheral sympathetic nerve activity, were reflected by significantly elevated plasma norepinephrine. In this animal DOCA administration produces a neurogenic form of hypertension which appears to be analogous to essential hypertension in man.