Effect of alpha-adrenergic blockade on the cardiovascular responses to hypoxemia and hypercapnic acidosis in conscious dogs.
In order to evaluate the role of the alpha-adrenergic system in the systemic and renal hemodynamic changes of the acute combined blood gas derangement, seven conscious mongrel dogs in careful sodium balance (80 mEq/day for 4 days) were evaluated. Each animal was evaluated during combined acute hypoxemia (PaO2 = 35 +/- 1 mm Hg) and hypercapnic acidosis (PaCO2 = 56 +/- 2 mm Hg; pH = 7.18 +/- 0.01) with (i) vehicle (D5W) alone and (ii) alpha 1-adrenergic blockade with prazosin, 0.1 mg/kg iv. Mean arterial pressure increased during the combined blood gas derangement with vehicle. In contrast, mean arterial pressure fell during combined acute hypoxemia and hypercapnic acidosis with alpha 1-adrenergic blockade. The mechanism for abrogation of the rise in mean arterial pressure during the combined blood gas derangement by alpha 1-adrenergic blockade appeared to be through attenuation of the rise in cardiac output rather than an exaggerated fall in total peripheral resistance. These observations suggest that the alpha-adrenergic system is important in circulatory homeostasis during the combined blood gas derangement.
Rose
C E
CE
Department of Internal Medicine, University of Virginia Medical Center, Charlottesville 22908.
Dougherty
M J
MJ
Brashers
V L
VL
Godine
R L
RL
Latham
L B
LB
Rose
K Y
KY
Carey
R M
RM
D000138:Acidosis / Q000209:etiology / Q000503:physiopathology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D002319:Cardiovascular System / Q000503:physiopathology*; D002496:Central Venous Pressure / Q000187:drug effects; D004285:Dogs; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006935:Hypercapnia / Q000150:complications*; D000860:Hypoxia / Q000503:physiopathology*; D011224:Prazosin / Q000494:pharmacology*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000502:physiology*; D012079:Renal Circulation / Q000187:drug effects; D012083:Renin / Q000097:blood; D013318:Stroke Volume / Q000187:drug effects; D014655:Vascular Resistance / Q000187:drug effects
D011942:Receptors, Adrenergic, alpha; D012083:Renin; D011224:Prazosin