Effects of Systemic and Local Phenylephrine and Arginine Vasopressin Infusions in Conscious Postnatal Sheep
| Autor: | Kevin Despain, Charles R. Rosenfeld, Sithembiso Velaphi, Timothy Roy |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Mean arterial pressure
Vasopressin medicine.medical_specialty Time Factors medicine.medical_treatment Blood Pressure Hindlimb Phenylephrine Heart Rate Internal medicine Heart rate medicine Animals Infusions Intra-Arterial Vasoconstrictor Agents Antihypotensive agent Sheep Domestic Sheep Dose-Response Relationship Drug business.industry Angiotensin II Arginine Vasopressin medicine.anatomical_structure Endocrinology Animals Newborn Pediatrics Perinatology and Child Health Vascular resistance business medicine.drug |
| Zdroj: | Pediatric Research. 58:58-65 |
| ISSN: | 1530-0447 0031-3998 |
| DOI: | 10.1203/01.pdr.0000163395.07153.90 |
| Popis: | Mean arterial pressure (MAP) increases after birth, however, the mechanisms remain unclear. Systemic angiotensin II (ANG II) infusions increase MAP in newborn sheep, but the direct effects of ANG II on peripheral vascular resistance (PVR) are minimal. Thus, its systemic pressor effects may reflect release of other pressor agents, e.g. α-agonists and/or AVP, suggesting they contribute to postnatal regulation of MAP and PVR. To address this, we performed studies in conscious sheep at 7–14, 15–21, and 22–35 d postnatal, infusing phenylephrine (PE) or AVP systemically or intra-arterially into the hindlimb while measuring MAP, heart rate (HR), and femoral blood flow (FmBF). Basal MAP and FmBF rose, whereas HR and femoral vascular resistance (FmVR) fell (p ≤ 0.03) during the first month postnatal. Although systemic PE and AVP dose dependently increased MAP and FmVR and decreased FmBF and HR (p < 0.001, ANOVA) at all ages, responses were not age dependent. Notably, increases in FmVR exceeded increases in MAP, and responses to PE appeared to exceed AVP (p < 0.05). Hindlimb infusions of both agents decreased FmBF and increased FmVR dose dependently (p < 0.001, ANOVA) at all ages without altering MAP or HR. These responses also were not age dependent. Unlike ANG II, PE and AVP directly increase PVR in newborn sheep. Moreover, FmVR increases more than MAP at all doses, suggesting these agonists may contribute to postnatal MAP regulation and could mediate the effects of systemic ANG II on postnatal MAP. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|