title: Angiotensin stimulates respiration in spontaneously hypertensive rats.
abstract: Spontaneously hypertensive rats (SHR) have an activated brain angiotensin system. We hypothesized 1) that ventilation (V) would be greater in conscious SHR than in control Wistar-Kyoto (WKY) rats and 2) that intravenous infusion of the ANG II-receptor blocker saralasin would depress respiration in SHR, but not in WKY. Respiration and oxygen consumption (VO(2)) were measured in conscious aged-matched groups (n = 16) of adult female SHR and WKY. For protocol 1, rats were habituated to a plethysmograph and measurements obtained over 60-75 min. After installation of chronic intravenous catheters, protocol 2 consisted of 30 min of saline infusion ( approximately 14 microliter. kg(-1). min(-1)) followed by 40 min of saralasin (1.3 microgram. kg(-1). min(-1)). V, tidal volume (VT), inspiratory flow [VT/inspiratory time (TI)], breath expiratory time, and VO(2) were higher, and breath TI was lower in "continuously quiet" SHR. In SHR, but not in WKY rats, ANG II-receptor block decreased V, VT, and VT/TI and increased breath TI. During ANG II-receptor block, an average decrease in VO(2) in SHR was not significant. About one-half of the higher V in SHR appears to be accounted for by an ANG II mechanism acting either via peripheral arterial receptors or circumventricular organs.
authors.affiliation: Department of Physiology, Queen's University, Kingston, Ontario, Canada K7L 3N6. jennings@post.queensu.ca
authors.forename: D B
authors.initials: DB
authors.lastname: Jennings
authors.forename: H J
authors.initials: HJ
authors.lastname: Lockett
mesh_terms: D000804:Angiotensin II / Q000502:physiology*; D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D005260:Female; D006973:Hypertension / Q000503:physiopathology*; D007320:Inspiratory Capacity; D010101:Oxygen Consumption / Q000187:drug effects; D012123:Pulmonary Ventilation / Q000187:drug effects; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012119:Respiration / Q000187:drug effects*; D012504:Saralasin / Q000494:pharmacology; D013990:Tidal Volume / Q000187:drug effects
chemical_list: D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000804:Angiotensin II; D012504:Saralasin