Hemodynamic profile of corticotropin-induced hypertension in the rat.
OBJECTIVE
To examine hemodynamic variables in corticotropin-induced hypertension in rats and the effects of reversal of the hypertension by L-arginine on the hemodynamic profile.


METHODS
Sixty male Sprague-Dawley rats were randomly divided into four groups: sham treatment (0.9% NaCl, injected subcutaneously); 0.5 mg/kg corticotropin per day, subcutaneously; 0.6% L-arginine in food plus sham; and L-arginine plus corticotropin. Systolic blood pressure, water and food intakes, urine volume, and body weight were measured every second day. After 10 days mean arterial blood pressure was measured by intra-arterial cannulation, and cardiac output, and renal, mesenteric, and hindquarter blood flows were determined using transonic small animal flowmeters.


RESULTS
Injection of corticotropin increased blood pressure, water intake, urine volume, and plasma sodium concentration, and decreased body weight and plasma potassium concentration. It increased cardiac output (P < 0.01), mesenteric blood flow (P < 0.05), and renal vascular resistance (P < 0.05), and decreased renal blood flow (P < 0.05), but did not change calculated total peripheral resistance, hindquarter blood flow, mesenteric or hindquarter vascular resistance. L-arginine prevented corticotropin-induced rises in blood pressure (P < 0.001) and renal vascular resistance (P < 0.05), and a fall in renal blood flow (P < 0.05), but did not affect other hemodynamic variables.


CONCLUSIONS
The hemodynamic profile of corticotropin-induced hypertension in the rat is characterized by a rise in cardiac output and renal vascular resistance, a fall in renal blood flow, but no change in total peripheral resistance, hindquarter blood flow, mesenteric vascular resistance, or hindquarter vascular resistance. L-arginine prevented corticotropin-induced rises both in blood pressure and in renal vascular resistance in the rat. These data suggest that the increase in renal vascular resistance might play a role in corticotropin-induced hypertension in the rat.
Wen
C
C
Department of Medicine, The St George Hospital, The University of New South Wales, Sydney, Australia.
Fraser
T
T
Li
M
M
Whitworth
J A
JA
D000324:Adrenocorticotropic Hormone / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006973:Hypertension / Q000139:chemically induced* / Q000503:physiopathology* / Q000517:prevention & control; D008297:Male; D009929:Organ Size / Q000187:drug effects; D011188:Potassium / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D012079:Renal Circulation / Q000187:drug effects; D012964:Sodium / Q000097:blood; D013152:Splanchnic Circulation / Q000187:drug effects; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects
D000324:Adrenocorticotropic Hormone; D001120:Arginine; D012964:Sodium; D011188:Potassium