title: Centrally mediated increased sympathetic activity is not important in the genesis of ACTH-induced hypertension in sheep.
abstract: 1. Adrenocorticotrophin (ACTH) administration to sheep produces a rapid adrenally dependent hypertension which is maximal after 3 days and associated with increased cardiac output (CO) and heart rate (HR), while calculated total peripheral resistance remains unchanged. 2. This study investigated the proposal that a centrally mediated increase in sympathetic activity is important in the development of ACTH-induced hypertension. 3. Concomitant intravenous infusions of either clonidine (60 micrograms/kg per day) or methyldopa (60 mg/kg per day) with ACTH (5 micrograms/kg per day) failed to inhibit the increase in mean arterial pressure (MAP) observed with ACTH. 4. In a separate experiment clonidine abolished the increase in CO and HR but not the pressor response associated with ACTH administration. 5. These results do not support a role for centrally mediated increase in sympathetic activity in the genesis of ACTH-induced hypertension.
authors.affiliation: Howard Florey Institute of Experimental Physiology and Medicine, Royal Melbourne Hospital, Parkville, Victoria, Australia.
authors.forename: C D
authors.initials: CD
authors.lastname: Spence
authors.forename: M
authors.initials: M
authors.lastname: Mathai
authors.forename: E H
authors.initials: EH
authors.lastname: Mills
authors.forename: J P
authors.initials: JP
authors.lastname: Coghlan
authors.forename: J A
authors.initials: JA
authors.lastname: Whitworth
authors.forename: B A
authors.initials: BA
authors.lastname: Scoggins
mesh_terms: D000324:Adrenocorticotropic Hormone; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D007275:Injections, Intravenous; D008750:Methyldopa / Q000494:pharmacology; D012756:Sheep; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D008750:Methyldopa; D000324:Adrenocorticotropic Hormone; D003000:Clonidine