Use of dextran-primed extracorporeal circuit in the canine model for venous return: with special references to the effects of two dihydropyridine-type Ca2+ channel blockers.
1. A successful canine "venous return (VR)" model is described, in which all hemodynamic parameters were stable for about an hour, by minimizing extracorporeal circuit primed with dextran (DX) so that the dilution of the blood was kept about 33%. 2. Increases in VR by norepinephrine (1 micrograms/kg) and dose-dependent decreases in VR by glyceryl trinitrate (1-30 micrograms/kg) were clearly observed. 3. While 1 microgram/kg of nifedipine produced a small, but significant decrease in VR, only a tendency for decrease was observed with higher doses which produced a definite fall in blood pressure. 4. Nisoldipine (1 microgram/kg) caused a small decrease in VR. However, higher doses that produced a large and persistent hypotension produced an increase in VR due probably to intense reflex translocation of the blood. The increase in VR was reversed with carvedilol, a beta-blocker with alpha-blocking activity.
Ishibashi
T
T
Department of Pharmacology, Niigata University School of Medicine, Japan.
Kato
K
K
Hamaguchi
M
M
Mitomi
A
A
Kawada
T
T
Imai
S
S
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003911:Dextrans / Q000494:pharmacology*; D004095:Dihydropyridines / Q000494:pharmacology*; D004285:Dogs; D005112:Extracorporeal Circulation; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009543:Nifedipine / Q000494:pharmacology; D015737:Nisoldipine / Q000494:pharmacology; D005996:Nitroglycerin / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology
D002121:Calcium Channel Blockers; D003911:Dextrans; D004095:Dihydropyridines; D015737:Nisoldipine; D005996:Nitroglycerin; D009543:Nifedipine; D009638:Norepinephrine