Further evidence for abnormal hindquarter tone in spontaneously hypertensive rats.
In spontaneously hypertensive rats (SHR) and normotensive control rats (NCR), hindquarter flow was observed in the conscious state with an electromagnetic flow probe chronically implanted around the terminal aorta. Arterial pressure was recorded with an indwelling catheter in the common carotid. When arginine vasopressin was infused intravenously at a rate of 12.5 ng/(kg.min), the increase in hindquarter resistance, calculated as arterial pressure divided by hindquarter flow, was significantly (p less than 0.005) augmented after ganglionic blockade with hexamethonium in SHR but not in NCR. This is explicable by assuming a tonic sympathetic vasoconstrictor activity in the hindquarters of SHR, reflexive inhibition of which partially offsets vasoconstrictor effect of infused vasopressin.
Iriuchijima
J
J
Department of Physiology, School of Medicine, University of Hiroshima, Japan.
D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000502:physiology; D005730:Ganglionic Blockers / Q000494:pharmacology; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D006614:Hindlimb / Q000098:blood supply*; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D005730:Ganglionic Blockers; D006584:Hexamethonium Compounds; D001127:Arginine Vasopressin; D018738:Hexamethonium