title: Fetal endocrine responses to prolonged reduced uterine blood flow are altered following bilateral sectioning of the carotid sinus and vagus nerves.
abstract: The present study examines the effect of carotid sinus/vagosympathetic denervation on fetal endocrine responses to prolonged reduced uterine blood flow (RUBF). Fetal sheep had vascular catheters inserted following bilateral sectioning of the carotid sinus and vagus nerves (denervated, n = 7) or sham denervation (intact, n = 7). Uterine blood flow was mechanically restricted at 126.1 +/- 0.7 days (mean +/- S.E.M.) for 24 h, decreasing arterial oxygen saturation by 47.3 +/- 2.6% (P < 0.01). Fetal plasma samples were obtained at -1, 3, 6, 12 and 24 h for subsequent analyses of arginine vasopressin (AVP), angiotensin II and catecholamines. The AVP response to prolonged RUBF was markedly attenuated in denervated fetuses (15.6 +/- 3.6 to 34.9 +/- 6.0 pg/ml) when compared with intact (10.0 +/- 1.4 to 127.3 +/- 28.4 pg/ml). In contrast, intact fetuses demonstrated no change in plasma angiotensin II concentrations with RUBF whereas denervated fetuses demonstrated a marked increase from 47.5 +/- 18.9 to 128.7 +/- 34.2 pg/ml. The norepinephrine and epinephrine responses to prolonged RUBF were attenuated in denervated fetuses (950.1 +/- 308.9 and 155.8 +/- 58.5 to 1268.3 +/- 474.6 and 290.6 +/- 160.2 pg/ml respectively) when compared with intact (1558.3 +/- 384.4 and 547.3 +/- 304.7 pg/ml to 3289.2 +/- 1219.8 and 896.8 +/- 467.8 pg/ml respectively). These results support a role for the peripheral chemoreceptors in mediating fetal endocrine responses to prolonged RUBF, which may in part lead to the altered cardiovascular responses observed in denervated fetuses under these conditions.
authors.affiliation: Department of Physiology, Lawson Research Institute, University of Western Ontario, London, Canada.
authors.forename: P E
authors.initials: PE
authors.lastname: Stein
authors.forename: S E
authors.initials: SE
authors.lastname: White
authors.forename: J
authors.initials: J
authors.lastname: Homan
authors.forename: L
authors.initials: L
authors.lastname: Fraher
authors.forename: H H
authors.initials: HH
authors.lastname: McGarrigle
authors.forename: M A
authors.initials: MA
authors.lastname: Hanson
authors.forename: A D
authors.initials: AD
authors.lastname: Bocking
mesh_terms: D000804:Angiotensin II / Q000097:blood; D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood; D002346:Carotid Sinus / Q000294:innervation*; D003714:Denervation; D004837:Epinephrine / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D005311:Fetal Hypoxia / Q000378:metabolism* / Q000662:veterinary*; D005333:Fetus / Q000378:metabolism*; D009638:Norepinephrine / Q000097:blood; D011247:Pregnancy; D012756:Sheep; D012757:Sheep Diseases / Q000378:metabolism*; D014599:Uterus / Q000098:blood supply; D014630:Vagus Nerve
chemical_list: D000804:Angiotensin II; D001127:Arginine Vasopressin; D009638:Norepinephrine; D004837:Epinephrine