Differential effects of chloral hydrate- and ketamine/xylazine-induced anesthesia by the s.c. route.
The proper use of anesthetics in animal experimentation has been intensively studied. In this study we compared the use of chloral hydrate (500 mg kg(-1)) and ketamine (167 mg kg(-1)) combined with xylazine (33 mg kg(-1)) by the s.c. route in male Wistar rats. Chloral hydrate and ketamine/xylazine produced a depth of anesthesia and analgesia sufficient for surgical procedures. The decrease of systolic and diastolic blood pressure was of a higher magnitude in rats anesthetized with chloral hydrate than with ketamine/xylazine. The initial microvascular diameter and blood flow velocity did not differ between both agents. On the other hand, ketamine/xylazine reduced the heart rate more intensively than chloral hydrate. Both anesthetics promoted an increase in arterial pCO(2) and a decrease in pH levels compared to unanesthetized animals. The blood glucose levels were of a higher magnitude in rats after ketamine/xylazine anesthesia than after chloral hydrate. In mesenteric arterioles studied in vivo, ketamine/xylazine anesthesia reduced the constrictive effect of noradrenaline and the dilator effect of bradykinin. However, both anesthetics did not modify the vasodilator effect promoted by acetylcholine. Based on our data, we concluded that both anesthetics alter metabolic and hemodynamic parameters, however the use of chloral hydrate in studies of microvascular reactivity in vivo is more appropriate since ketamine/xylazine reduces the responses to vasoactive agents and increases blood glucose levels.
Rodrigues
Stephen F
SF
Laboratory of Hypertension, Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, 05508-900, Av. Prof. Lineu Prestes, 1524 São Paulo, SP, Brazil.
de Oliveira
Maria Aparecida
MA
Martins
Joilson O
JO
Sannomiya
Paulina
P
de Cássia Tostes
Rita
R
Nigro
Dorothy
D
Carvalho
Maria Helena C
MH
Fortes
Zuleica Bruno
ZB
D000758:Anesthesia / Q000379:methods*; D000778:Anesthetics, Dissociative / Q000494:pharmacology*; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D001920:Bradykinin / Q000494:pharmacology; D002245:Carbon Dioxide / Q000097:blood; D002697:Chloral Hydrate / Q000494:pharmacology*; D004336:Drug Antagonism; D004338:Drug Combinations; D006339:Heart Rate / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007279:Injections, Subcutaneous; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D008833:Microcirculation / Q000187:drug effects / Q000503:physiopathology; D009638:Norepinephrine / Q000494:pharmacology; D011659:Pulmonary Gas Exchange; D051381:Rats; D017208:Rats, Wistar; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology; D014991:Xylazine / Q000494:pharmacology*
D000778:Anesthetics, Dissociative; D018686:Anesthetics, Intravenous; D001786:Blood Glucose; D004338:Drug Combinations; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D002245:Carbon Dioxide; D014991:Xylazine; D002697:Chloral Hydrate; D007649:Ketamine; D001920:Bradykinin; D009638:Norepinephrine