Induction of anesthesia is accompanied by modest hyperglycemia and a decreased plasma insulin concentration. Most insulin is secreted in discrete pulses occurring at approximately 6- to 8-min intervals. We sought to test the hypothesis that anesthesia inhibits insulin release by disrupting pulsatile insulin secretion in a canine model by use of direct portal vein sampling. We report that induction of anesthesia causes an abrupt decrease in the insulin secretion rate (1.1 +/- 0.2 vs. 0.7 +/- 0.1 pmol. kg(-1). min(-1), P < 0.05) by suppressing insulin pulse mass (630 +/- 121 vs. 270 +/- 31 pmol, P < 0.01). Anesthesia also elicited an approximately 30% higher increase in insulin pulse frequency (P < 0.01) and more orderly insulin concentration profiles (P < 0.01). These effects were evoked by either sodium thiamylal or nitrous oxide and isoflurane. In conclusion, anesthesia represses insulin secretion through the mechanism of a twofold blunting of pulse mass despite an increase in orderly pulse frequency. These data thus unveil independent amplitude and frequency controls of beta-cells' secretory activity in vivo.
Purpose:To test the accuracy of pulse oximetry and capnometry aboard a moving ambulance in a cardiogenic shock model. Methods: Five dogs were anesthetized with pentobarbital, intubated, and instrumented. Stepwise worsening cardiogenic shock was induced with esmolol until cardiac output dropped 75%, then reversed in steps. An arterial blood gas specimen and hemodynamic measurements were taken at each step. Weeks later, the experiment was repeated aboard a moving ambulance on four dogs; shock was induced quickly and reversed slowly. O2 saturation was estimated by pulse oximetry and pCO 2 by end-tidal CO 2 Differences between the noninvasive estimate and the blood gas measurements (measurement error) were compared statistically. Results: Pulse oximetry and capnometry usually were accurate, but some highly erroneous readings occurred. Pulse oximetry readings sometimes were unavailable, especially during profound shock.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.