CATECHOLAMINE RESPONSE TO CHRONIC ANG-II INFUSION AND ITS ROLE IN MYOCYTE AND CORONARY VASCULAR DAMAGE

Acute elevations in circulating angiotensin II (ANG II) are known to i ncrease circulating norepinephrine (NE) levels. However, the time cour se of catecholamine release relative to chronic ANG II infusion is not known. Furthermore, it is unknown if this ANG II-induced catecholamin e release is ANG II type 1(AT(1)) receptor mediated or whether the inc rease in serum catecholamines is responsible for the myocyte and coron ary vascular damage seen within the first 3 days of chronic ANG II inf usion. Therefore, we examined the influence of chronic ANG II stimulat ion on serum catecholamine levels with and without AT(1) blockade and the effect-of P-blockade on ANG II-induced myocyte and coronary vascul ar damage, The results indicate that NE release is ATI mediated, but N E is not significantly elevated until day 4 of ANG II infusion after w hich it remains elevated. 6-Blockade prevented most ANG II-related myo cyte necrosis and coronary vascular damage. Therefore, myocyte and cor onary vascular damage do not appear to be related to increased serum N E levels, but instead may be due to the release of neural catecholamin es within the heart.