Abstract
Hemorrhage (H) has been reported to stimulate AVP release in the fetal lamb. To examine the determinants and time course of the fetal response to H, 7 chronically catheterized fetuses of 92-116 days gestation were hemorrhaged 15-20% of blood volume at a rate of 2%/min. Heart rate, arterial PO2, PCO2 and pH did not change. Serum AVP, osmolality and hematocrit were drawn at 10 min intervals for 60 min. Blood volume sampled was replaced immediately with fetal blood. AVP was measured by radioimmunoassay. Assay cross reactivity with arginine vasotocin and angiotensin II was negligible. During H, mean systemic arterial pressure (SAP) fell 24% from 40±1 to 30±2 torr (p<.01). Serum osmolality did not change H, but rose from 293±1.2 to 298±1.9 mOs (p<.05) by 30 min. Serum AVP levels showed a biphasic response. The base line AVP value of 1.6±.20 pg/ml rose to 27.9±14.9 (p<.01) by the end of H (10 min), then declined to 16.6±4.8 pg/ml at 20 min before rising again to 34.2±12.8 pg/ml by 30 min. Immediately after H, serum AVP correlated inversely with SAP change (r=.58), and not with serum osmolality (r=.12). By 30 min AVP correlation with SAP change was non-existent (r=.05) while a strong positive correlation between osmolality and serum AVP was found (r=.87). We conclude that the biphasic shape of the fetal AVP response curve to a single H represents a dual response, the first phase triggered mainly by falling SAP and the second phase by increased serum osmolality.
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Drummond, W., Rudolph, A., Keil, L. et al. 179 FETAL LAMB ARGININE VASOPRESSIN (AVP) RESPONSE TO A SINGLE HEMORRHAGE. Pediatr Res 12 (Suppl 4), 393 (1978). https://doi.org/10.1203/00006450-197804001-00184
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DOI: https://doi.org/10.1203/00006450-197804001-00184