title: Response of the rat cremaster microcirculation to hemorrhage in vivo: differential effects of intravenous anesthetic agents.
abstract: Anesthetic agents are known to have differential effects on both the systemic circulation and the microcirculation. The aim of this study was to compare the effects of several intravenous (i.v.) agents on the microcirculatory response to hemorrhage. Male Wistar rats (n = 52) were anesthetized i.v. either with propofol and fentanyl (propofol fentanyl), ketamine, or thiopental. Cardiovascular variables were monitored. The cremaster muscle was observed by using fluorescent intravital microscopy. FITC-BSA was administered (0.25 mL/100 g, i.a.) to determine macromolecular leak, an index of vessel integrity. Animals were further allocated into control (C), 10% hemorrhage (H), or hemorrhage re-infusion (H-R, removal of 10% blood volume and then re-infusion of saline and blood) groups. When systolic arterial pressure (SAP) was maintained after hemorrhage, constriction of A3 and A4 arterioles (5-30 microm) was accompanied by no change in the diameter of A1 (80-130 microm): most frequent with ketamine (A1: -1.7 +/- 1.2; A4: -13.9 +/- 2.7%; H and H-R: n = 9/11). With lower SAP, dilation of the A3 and A4 was accompanied by constriction of the A1: most frequent with propofol/fentanyl (A1: -8.0 +/- 2.5; A4; 35.1 +/- 9.4%; H and H-R: n = 6/11). No increases in macromolecular leak occurred with any anesthetic agent or in H or H-R groups. The response of cremaster muscle microcirculation to hemorrhage differs with different i.v. anesthetic agents. Dilation of small arterioles is the predominant response with propofol/fentanyl and constriction of small arterioles with ketamine.
authors.affiliation: Section of Surgical and Anaesthetic Sciences, University of Sheffield, Royal Hallamshire Hospital, Sheffield S10 2JF, United Kingdom.
authors.forename: Zoë L S
authors.initials: ZL
authors.lastname: Brookes
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Brown
authors.forename: Charles S
authors.initials: CS
authors.lastname: Reilly
mesh_terms: D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001784:Blood Gas Analysis; D006439:Hemodynamics / Q000187:drug effects; D006470:Hemorrhage / Q000503:physiopathology*; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D008833:Microcirculation / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000187:drug effects*; D009599:Nitroprusside / Q000494:pharmacology; D015742:Propofol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013874:Thiopental / Q000494:pharmacology
chemical_list: D018686:Anesthetics, Intravenous; D009599:Nitroprusside; D007649:Ketamine; D013874:Thiopental; D015742:Propofol