Abstract
The conclusion [1] that the presence of the kidneys may be more important in the regulation of arterial pressure in immature than adult rabbits suggested the desirability of measuring changes of augiotension H-like activity in arterial blood in response to hemorrahge. Angiotension H-like activity was measured by the shortening of a rat's ascending colon, irrigated intraluminally with pronethalol 1 mg/min. The colon was superfused with arterial blood from the rabbit in an external circuit, from which the blood was returned to a jugular vein [2]. The colon was calibrated by infusion of Hypertension (Ciba) before withdrawl of 25% of the rabbit's calculated blood volume. After 30 min. the blood volume was restored with dextran and the calibration were repeated. Angiotension H-like activity developing during hemorrhage in 6 adult rabbits was equivalent to 0.31 ± 0.07 ng/ml Hypertension, whereas that in 10 immature rabbits averaged 1.76 ± 0.41 ng/ml (P < 0.025). Although Hypertensin is inactivated slightly less rapidly in immature rabbits, the difference is insufficient to account for the very much greater rise in angiotensin H-like activity seen during hemorrhage in immature than in adult rabbits.
1. MOTT, J. C.: J. Physiol., 202: 25 (1969).
2. VANE, J. R.: Brit. J. Pharmacol. Chemother., 35: 209 (1969).
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Brougition-Pipkin, F., Mott, J. 49. Changes in angiotensin H-like activity in arterial blood induced by hemorrhage in immature and adult rabbits. Pediatr Res 5, 93 (1971). https://doi.org/10.1203/00006450-197102000-00054
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DOI: https://doi.org/10.1203/00006450-197102000-00054