Different sensitivity to the suppressive effects of isoflurane anesthesia on cardiorespiratory function in SHR/Izm, WKY/Izm, and Crl:CD (SD) rats.
Isoflurane is a widely used anesthetic, but its effects with increase in inspired concentration on cardiovascular function have not yet been clarified in rodents. Additionally, there are only a few studies comparing isoflurane-induced cardiorespiratory effects between rat strains. Thus, we investigated the differences in cardiorespiratory responsiveness to increasing concentration of inspired isoflurane in SHR/Izm, WKY/Izm and Crl:CD (SD) rats, by increasing the setting values of vaporizer's dial indicator. The rats were anesthetized with 1.5% isoflurane, and electrocardiograms, blood pressure, and respiratory rate were recorded simultaneously. Thereafter, the inspired concentration was increased stepwise to 2%, 3%, 4%, and 5%, and cardiorespiratory parameters were obtained at each concentration. Under anesthesia at more than 4%, although prolongation of the RR and PR intervals was observed in all strains, shortening of the QTCinterval was found only in SHR/Izm rats. From frequency domain analysis of heart rate variability, an increase in LF/HF ratio and a decrease of HF components were observed in SHR/Izm and WKY/Izm rats, respectively, with 5% isoflurane anesthesia. Blood pressure and heart rate were remarkably reduced in SHR/Izm rats at higher concentrations, whereas the reduction was smallest in WKY/Izm rats among the three strains examined. Respiratory rate was inspired concentration-dependently decreased in all strains. These results suggested that SHR/Izm rats are more sensitive to suppressive effects of isoflurane anesthesia on cardiovascular function among these rat strains.
Center for Laboratory Animal Science, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan.
Kouki
K
Kato
Jun
J
Wakai
Kazunori
K
Ozawa
Miho
M
Sekiguchi
Kiyoaki
K
Katahira
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography; D006339:Heart Rate / Q000187:drug effects*; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D056152:Respiratory Rate / Q000187:drug effects*
D018685:Anesthetics, Inhalation; D007530:Isoflurane