Direct observation of skeletal muscle blood vessels (rat cremaster)

Abstract

The recent description of the rat's cremaster muscle by Majno, Palade & Schoefl (1961) suggested that this muscle might provide a suitable site for direct observation of skeletal muscle blood vessels in the living animal. This proved to be so and the method developed allows the study of the reactions of the vessels to various stimuli applied topically and intravenously. It is thought that the vessels are seen in a state that, for a time at least, is nearly normal for resting skeletal muscle. The only comparable preparations that I can trace are those of Zweifach & Metz (1955a, b) and Hyman & Paldino (1962), but their observations do not cover the same ground as those now reported.The observations are directed more to exploring the possibilities of the method than to solving particular problems. They show, however, that in general the vascular reactions, in terms of dilatation and constriction, are in keeping with those derived from blood flow studies in man and other animals. They also show that the dilatation resulting from the intravenous administration of adrenaline affects mainly the arteries, as with acetylcholine, rather than the minute vessels, as with histamine. METHODS Animals. A rat of about 100 g body weight is anaesthetized with urethane (150 mg) sometimes with pentobarbitone sodium (3-0 mg) injected intraperitoneally, and placed on its back on a cork mat with the hind legs widely splayed. Body temperature is regulated by an electric lamp placed above and moved nearer or further away as required. Temperatures are measured by a thermo-electric thermometer (copper-constantan junctions); body temperature from a polythene covered junction inserted into the colon about 5 cm beyond the anus, tail temperature (when required) by a junction attached near its tip with zinc oxide plaster; that of the fluid irrigating the exposed muscle by a junction attached to the tip of the irrigating tube (Text- fig. 2).Blood pressure is measured (when required) from the carotid artery through a polythene tube, 0-58 mm internal diameter (PE 50, Clay Adams Inc., New York) and about 4 cm long, joined by a 3 mm (about) internal diameter tube (PE 330) to a miniature membrane manometer like that described by Sherrington (1919). Ringer's solution with heparin (10 u./ml.) perfused through the manometer at a rate of 0 5-1 0 ml./hr prevents clotting in the tube tip.

Sensory and Autonomic Neurons Project Both to the Smooth Retractor Penis and to the Striated Bulbospongiosus Muscles. Neurochemical Features of the Sympathetic Subset

“…The autonomic control of vasomotor functions could be involved in the muscles metabolism (Grant, 1966;Baez, 1973;Fleming et al, 1987Fleming et al, , 1989Franken et al, 1996;Berg et al, 1997;Kurjiaka, 2004). In fact, during the contraction of a muscle it is possible to observe a local functional vasodilatation, quickly followed by a sympathetic vasoconstriction (Thomas and Segal, 2004).…”

An anatomical and electrophysiological study of the genitofemoral nerve and some of its targets in the male rat

“…In the male rat the GFn has been variously reported to arise from lumbar spinal nerves 2 and 3 (Greene, 1955;Clegg & Doyle, 1966;Grant, 1966), and lumbar spinal nerves 1 and 2 (Hodson, 1970;Hebel & Stromberg, 1986), confirmed more recently by the use of immunohistochemical techniques (Nagy & Senba, 1985;Wang et al 1989; Kar et al 1990). Running caudally, the lumbar spinal nerves converge to form the GFn proper.…”

“…The femoral branch has been reported to innervate the inguinal skin in the rat (Greene, 1955;Clegg & Doyle, 1966;Hebel & Stromberg, 1986) and humans (Hollinshead & Rosse, 1985;Reid & Cros, 1999) and the scrotal skin in the rat (Clegg & Doyle, 1966), and the genital branch also to innervate the scrotal skin in the rat (Greene, 1955;Clegg & Doyle, 1966;Nagy & Senba, 1985;Hebel & Stromberg, 1986) and humans (Reid & Cros, 1999), the cremaster muscle (Cm) surrounding the testes in the rat (Greene, 1955;Clegg & Doyle, 1966;Grant, 1966;Adams et al 1967;Hebel & Stromberg, 1986) and humans (Hollinshead & Rosse, 1985;Reid & Cros, 1999), the spermatic cord and vaginal tunica of the testes in the rat (Durwood, 1964;Miller et al 1964), and the dartos muscle lining the scrotal sac in humans (Mitchel, 1938;Clegg & Doyle, 1966). However, more recently it has been reported in the rat that the scrotum is innervated by branches of the pudendal nerve (Pacheco et al 1997;McKenna & Nadelhaft, 1986) and not by the GFn.…”

Effects of Vasodilators on Microcirculation of the Rat Cremaster Muscle: A Microscopic Method for Screening Drugs

“…Grant (1) and Majno et al (2) proposed that the vasculature of the rat cremaster muscle is an appropriate model for the purpose of observing microcirculation in the striated muscle in vivo. The histological structure of the rat cremaster muscle is similar to one of the skeletal muscles of the extremeties, and the vas culature of the cremaster is innervated by the sympathetic nerve (1,3). By removing only the fascia of the cremaster muscle, the microcirculation can be easily observed without complicated manipulations.…”

“…administration of these two drugs, arteriolar vasoconstriction was observed. Grant (1) showed that adrenaline given i.v. caused arterial dilatation of the rat cremaster though this sympathomimetic constricted the artery when applied topically .…”