Metabolism and synthesis of arginine vasopressin in conscious newborn sheep

Darryl C. Miao, Sithembiso C. Velaphi, Timothy Roy, Kevin DeSpain, Charles R. Rosenfeld

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Arginine vasopressin (AVP) is an important regulator of cardiovascular homeostasis in the fetus, but its role after birth is unclear. Although infused AVP increases mean arterial pressure (MAP) during the 1st mo after birth, pressor responses are unchanged, suggesting that vascular responsiveness is also unchanged. Alternatively, this could reflect increases in AVP metabolic clearance rate (MCRAVP). However, newborn AVP metabolism and synthesis are poorly studied. Therefore, we examined the pressor responses to infused AVP and the pattern of circulating AVP, AVP production rate (PR AVP), and MCRAVP in conscious newborn sheep (n = 5) at 9-38 days after birth. Basal MAP rose and heart rate (HR) fell during the study period (P ≤ 0.02), while circulating AVP was unchanged (P > 0.1), averaging 3.01 ± 0.86 pg/ml. Infused AVP elicited steady-state responses at 10-40 min, increasing plasma AVP and MAP and decreasing HR (P < 0.001). Although pressor responses were unchanged between 9 and 38 days, the rise in MAP correlated with increases in plasma AVP (R = 0.47, P = 0.02, n = 24). MCR AVP was unchanged throughout the 1st mo (P < 0.2), averaging 205 ± 17 ml·kg-1·min-1, and was associated with an elevated PRAVP, 973 ± 267 pg·kg -1·min-1, which also was unchanged (P < 0.1). After birth, MCRAVP and PRAVP are elevated, probably accounting for the stable plasma AVP levels. The former is also likely to account for the stable pressor responses to infused AVP during the 1st mo. The reason for the elevated PRAVP is unclear but may relate to increases in vascular volume associated with postnatal growth.

Original languageEnglish (US)
Pages (from-to)E672-E677
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume295
Issue number3
DOIs
StatePublished - Sep 2008

Keywords

  • Arginine vasopressin production rate
  • Metabolic clearance rate
  • Neonatal blood pressure

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)

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