Metabolism and synthesis of arginine vasopressin in conscious newborn sheep
| Autor: | Darryl C. Miao, Charles R. Rosenfeld, Timothy Roy, Kevin Despain, Sithembiso Velaphi |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2008 |
| Předmět: |
medicine.medical_specialty
Vasopressin Mean arterial pressure endocrine system Aging Arginine Physiology Metabolic Clearance Rate Endocrinology Diabetes and Metabolism Neuropeptide Hemodynamics Blood Pressure Growth Biology Heart Rate Physiology (medical) Internal medicine medicine Animals Homeostasis Fetus Sheep urogenital system Articles Arginine Vasopressin Blood pressure Endocrinology nervous system Animals Newborn hormones hormone substitutes and hormone antagonists |
| Popis: | 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 (PRAVP), 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). MCRAVP 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. |
| Databáze: | OpenAIRE |
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