title: Acute hypoxic pulmonary vasoconstriction in conscious dogs decreases renin and is unaffected by losartan.
abstract: Acute hypoxic pulmonary vasoconstriction (HPV) may be mediated by vasoactive peptides. We studied eight conscious, chronically tracheostomized dogs kept on a standardized dietary sodium intake. Normoxia (40 min) was followed by hypoxia (40 min, breathing 10% oxygen, arterial oxygen pressures 36 +/- 1 Torr) during both control (Con) and losartan experiments (Los; iv infusion of 100 microg. min-1. kg-1 losartan). During hypoxia, minute ventilation (by 0.9 l/min in Con, by 1.3 l/min in Los), cardiac output (by 0.36 l/min in Con, by 0.30 l/min in Los), heart rate (by 11 beats/min in Con, by 30 beats/min in Los), pulmonary artery pressure (by 9 mmHg in both protocols), and pulmonary vascular resistance (by 280 and 254 dyn. s. cm-5 in Con and Los, respectively) increased. Mean arterial pressure and systemic vascular resistance did not change. In Con, PRA decreased from 4.2 +/- 0.7 to 2.5 +/- 0.5 ng ANG I. ml-1. h-1, and plasma ANG II decreased from 11.9 +/- 3.0 to 8.2 +/- 2.1 pg/ml. The renin-angiotensin system is inhibited during acute hypoxia despite sympathetic activation. Under these conditions, ANG II AT1-receptor antagonism does not attenuate HPV.
authors.affiliation: Experimental Anesthesia, Clinic of Anesthesiology and Operative Intensive Care Medicine, 13353 Berlin, Germany.
authors.forename: M O
authors.initials: MO
authors.lastname: Krebs
authors.forename: W
authors.initials: W
authors.lastname: Boemke
authors.forename: S
authors.initials: S
authors.lastname: Simon
authors.forename: M
authors.initials: M
authors.lastname: Wenz
authors.forename: G
authors.initials: G
authors.lastname: Kaczmarczyk
mesh_terms: D000804:Angiotensin II / Q000097:blood; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001639:Bicarbonates / Q000097:blood; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000502:physiology; D004032:Diet; D004285:Dogs; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology*; D019808:Losartan / Q000494:pharmacology*; D010953:Plasma Volume / Q000502:physiology; D011652:Pulmonary Circulation / Q000502:physiology*; D012083:Renin / Q000097:blood*; D015656:Respiratory Mechanics / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology; D014661:Vasoconstriction / Q000502:physiology*
chemical_list: D000959:Antihypertensive Agents; D001639:Bicarbonates; D000804:Angiotensin II; D012083:Renin; D019808:Losartan