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Is atriopeptin a physiological or pathophysiological substance? Studies in the autoimmune rat
J E Greenwald1, M Sakata, M L Michener
1Department of Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110.
The Journal of Clinical Investigation
|April 1, 1988
Summary
Autoimmune rats lacking atriopeptin (AP) showed inhibited natriuresis during acute volume expansion but not chronic salt loading. AP deficiency did not affect hypertension or mineralocorticoid escape, suggesting a limited role in these processes.
Area of Science:
- Cardiovascular Physiology
- Renal Physiology
- Endocrinology
Background:
- Atriopeptin (AP) is a peptide hormone synthesized in mammalian atria with known natriuretic, diuretic, and vasodilatory effects.
- The precise physiological and pathophysiological roles of AP in cardiovascular regulation remain incompletely understood.
- Understanding AP's function is crucial for addressing conditions involving fluid and electrolyte balance.
Purpose of the Study:
- To investigate the physiological and pathophysiological consequences of prolonged atriopeptin deficiency.
- To elucidate the role of AP in natriuresis during acute and chronic volume expansion.
- To determine AP's involvement in blood pressure regulation and mineralocorticoid escape.
Main Methods:
- Development of an autoimmune rat model sensitized against endogenous atriopeptin (AP).
- Assessment of natriuretic responses to acute intravenous volume expansion and chronic oral salt loading.
- Evaluation of AP levels in spontaneously hypertensive rats and the impact of immunization on hypertension development.
- Analysis of mineralocorticoid escape during desoxycorticosterone acetate administration in immunized and control rats.
Main Results:
- Autoimmune rats exhibited inhibited natriuresis following acute intravenous volume expansion.
- Natriuresis in response to chronic oral salt loading was not suppressed in autoimmune rats.
- Plasma AP levels increased with blood pressure in spontaneously hypertensive rats, but immunization had no effect on hypertension or sodium excretion.
- Prior immunization against AP did not alter the mineralocorticoid escape phenomenon.
Conclusions:
- Atriopeptin plays a significant role as a natriuretic substance specifically in response to acute intravascular volume loading.
- AP does not appear to be critically involved in the natriuretic response to chronic volume loading, blood pressure regulation, or mineralocorticoid escape.
- These findings refine our understanding of atriopeptin's specific contributions to cardiovascular homeostasis.
