A modified ATPase method for the simultaneous demonstration of capillaries and fiber types in skeletal muscle is presented. Muscle biopsies were obtained from mice, hamsters, rats, cats, and dogs, quick frozen, and sectioned at 8 microns in a cryostat. The frozen slides were fixed in a neutral formalin solution at 4 C for 5 min, and then incubated at 37 C for 1 hr in a medium containing ATP, Pb2+, and Ca2+ in a tris-maleate buffer (pH 7.2). Dilute (NH4)2S was used as a developer. To test the reliability of the proposed method, serial sections of each biopsy were stained separately for capillaries (amylase-PAS method) and for fiber types by a standard myosin ATPase (m-ATPase) method. Fiber type percent and capillary parameters were determined for each biopsy. No difference in results was observed for parameters determined using the modified ATPase method compared to the standard capillary and fiber type staining methods. This modified technique is therefore suitable for the simultaneous demonstration of capillaries and fiber types in skeletal muscle.

This study was conducted to quantify and compare the extent of fibre degenerative and regenerative processes in different muscles of the rat hindlimb following single or repeated daily bouts of treadmill exercise. Wistar rats were used as non-exercised controls, or subjected to one, five, or ten (n = 8 per group), 30-minute daily bouts (-16 degrees, 12-15m.min-1) of downhill exercise. Soleus (S), vastus lateralis (VL), medial gastrocnemius (MG), plantaris (P), and tibialis anterior (TA) muscles were analyzed from transverse cryosections stained with either H&E for morphological alterations indicative of fibre degeneration or regeneration, or mATPase activity for determination of fibre type. Results showed that in all groups, the percentage of morphologically altered fibres (%AF) was greater in S (4-8%) than in MG, VL, P, or TA (1-2%). The %AF across all muscles was greater following only one, versus multiple exercise bouts, or versus no exercise. The proportions of AF of different histochemical types followed the same distribution as the fibre type in the muscle area examined. These direct assessments indicate that the extent of fibre degenerative and regenerative processes varies among the different muscles involved, and is greater following a single bout, compared to repeated daily bouts of exercise.

The purpose of this study was to investigate the significance of fiber type and the effects of the duration of ischemia on metabolic and contractile function of skeletal muscle. Under anesthesia, the distal tendons of the fast twitch extensor digitorum longus (EDL) and slow twitch soleus (SOL) muscles of the right hindlimb of female Wistar rats (250 to 300 gm) were connected to force transducers. Rats were assigned to group 1, 1 hour of ischemia; group 2, 2 hours of ischemia; or group 3, 3 hours of ischemia (n = 10 for each group). After ischemia, muscles were assessed for 2 hours of reperfusion. In both muscles, isometric twitch (Pt) and tetanus (Po) and 11 metabolic parameters were measured and compared with controls. After 1, 2, or 3 hours of ischemia Pt and Po were significantly (p < 0.05) lower than preischemic values. After 2 hours of reperfusion, forces and metabolic parameters of group 1 recovered to preischemic levels. However, contractile function of either muscle failed to recover fully after 2 hours of ischemia and 2 hours of reperfusion (SOL: Pt = 43.7 +/- 12 percent of initial; EDL: Pt = 32.2 +/- 9.2 percent) or after 3 hours of ischemia and 2 hours of reperfusion (SOL: Pt = 26.8 +/- 11 percent of initial; EDL: Pt = 19.3 +/- 6.8 percent). Although ADP and AMP recovered to preischemic levels in both muscles after 2 hours of ischemia and 2 hours of reperfusion, ATP recovered to just 70 percent in the soleus muscles (13.4 +/- 1.7 mmol/kg dry weight) and 60 percent in the extensor digitorum longus muscles (17.93 +/- 4.1 mmol/kg dry weight). After 3 hours of ischemia and 2 hours of reperfusion, ATP was further significantly (p < 0.05) decreased in the soleus muscles (48 percent initial) but not in the extensor digitorum longus muscles. Significant partial correlation coefficients (p < 0.005) were obtained between ATP levels and Pt (SOL: r = 0.757; EDL: r = 0.619) or Po (SOL: r = 0.810; EDL: r = 0.759). For this rat hindlimb model, we conclude that both fiber type and the duration of ischemia significantly affect metabolic and contractile function.

Many published papers have noted peripheral vasoconstrictive effects of cigarette smoking. In fact, smoking even a single cigarette can significantly reduce digital blood flow.' Smoking cigarettes on a chronic basis has been indicted as an etiologic factor in chronic ulcers of the extremities. We have witnessed the healing of a chronic finger-tip ulcer following abstinence from a three-pack-per-day cigarette habit in one patient? We have also demonstrated a temporary delay in wound healing in excised wounds on the ears of rabbits compared with a control groupP Although there is little that has been published on this, many surgeons have noted the deleterious effects of cigarette smoking after microvascular procedures, particularly replantation. More than 500 compounds have been isolated from the particulate and gaseous phases of tobacco smoke. Nicotine has been suspected as being the major villain in vasoconstriction.To test our hypothesis that nicotine ingestion could effect the survival of replants, we performed the following experiment in the Microsurgical Research Unit at the University of Toronto. One ear on each of 20 male New Zealand white rabbits was severed and replanted. Ten of these rabbits served as controls. The remaining ten rabbits received megaphysiologic doses of nicotine (2 mg/kg) subcutaneously twice daily for five preoperative and ten postoperative days. Some of the rabbits treated with the nicotine demonstrated convulsive reactions to the injections, however, each rabbit postoperatively developed good capillary refill in the replanted ear within an hour and all of the replanted ears survived in both the control and the treated group alike. Our results were surprising and unexpected.We are not ready to advocate cigarette smoking in patients undergoing replantation based on this one experiment as we do not feel we have perfected our model, and we are planning a better model to continue our investigations. We wish to report the negative result of our present endeavor to spare other investigators the time and effort we have entered into this study. Until an improved model can be developed that more closely approximates the actual situation of cigarette smoking in humans, clinical observations should certainly take precedence over findings in this experimental study.