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STIMULATION OF THE GASTRIC SODIUM MONITOR REDUCES HEPATIC ANGIOTENSIN‐CONVERTING ENZYME ACTIVITY
Author(s) -
Duggan KA,
Ye VZC
Publication year - 1997
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1997.tb01222.x
Subject(s) - stimulation , chemistry , enzyme , renin–angiotensin system , angiotensin ii , endocrinology , medicine , sodium , pharmacology , biochemistry , receptor , blood pressure , organic chemistry
SUMMARY 1. The natriuresis engendered by stimulation of the gastric sodium monitor is mediated in part by a decrease in the circulating concentration of angiotensin II (AngII). This decrease is due to a decrease in synthesis rather than to an increase in metabolism. We investigated the role of changes in plasma and hepatic angiotensin‐converting enzyme (ACE) activity in this decrease in AngII synthesis. 2. Male Sprague‐Dawley rats were equilibrated on a low‐sodium diet for 7 days. On the day of experiment, rats were anaesthetized and received either a sodium load of 1.5 mmol/kg as 3 mol/L saline or an equivalent volume of an iso‐osmotic urea solution by direct gastric puncture. Blood was sampled and livers were harvested at 0 and 30 min after sodium or urea administration. Angiotensin‐converting enzyme was measured in serum and tissue homogen‐ates by generation of histidyl‐leucine. 3. In the liver, ACE activity decreased from control after both sodium ( P < 0.005) and urea ( P < 0.025) administration. The decrease was greater in the group that received saline compared with rats that received urea ( P < 0.05). Serum ACE decreased in response to urea ( P < 0.025) but not sodium administration. 4. We conclude that stimulation of the gastric sodium monitor results in a decrease in ACE activity in the liver. This decrease in ACE activity may be contributory to the decrease in AngII synthesis.