A novel model of acute murine hindlimb ischemia

1 Department of Surgery, Division of Vascular and Endovascular Surgery; and 2 Division of Plastic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts Submitted 4 June 2006 ; accepted in final form 21 September 2006 The McGivney hemorrhoidal ligator (MHL), a band designed to cause tissue necrosis, is the preferred experimental tool to create hindlimb ischemia-reperfusion (I/R) injury in rodents. This report defines and compares the ex vivo band tension exerted by MHL and orthodontic rubber bands (ORBs) along with select in vivo characteristics of I/R. As to method, ex vivo band tension was measured over relevant diameters using a tensiometer. In vivo assessment of murine limb perfusion during ischemia with ORB and MHL was compared using laser Doppler imaging and measurement of wet weight-to-dry weight ratio. Neuromuscular scoring and histological extent of muscle fiber injury after I/R with MHL and ORB were also compared. A dose-response curve, between the duration of ORB-induced I/R with both mitochondrial activity (methyl-thiazol-tetrazolium) or tail perfusion [laser Doppler imaging (LDI)], was generated. As a results, ex vivo measurements showed that ORB exerted significantly less force than the MHL. Despite less tension in ORB, in vivo testing of the ORB confirmed complete ischemia by both LDI and wet weight-to-dry weight ratio. After I/R, caused by ORB, there was significantly less neuromuscular dysfunction. Histological assessment confirmed similar degrees of muscle fiber injury after I/R with either the MHL or ORB. Increasing durations of ischemia created by the ORB followed by reperfusion significantly decreased mitochondrial activity and tail perfusion after 24 h of ischemia. In conclusions, ORB produced similar levels of tissue ischemia in murine models of limb I/R with fewer levels of nonspecific injury. ORB may be the preferred model for selected studies of limb I/R. tourniquets; skeletal muscle Address for reprint requests and other correspondence: M. T. Watkins, Div. of Vascular and Endovascular Surgery, Massachusetts General Hospital, 15 Parkman St., Ste. 458, Boston, MA 02114 (e-mail: mtwatkins{at}partners.org )