Effect Of Muscular Contraction Research Articles

Effect of Muscular Contraction on Magnetization Transfer Detected at 1.5T

The effect of rigor (formation of actomyosin complexes) on magnetization transfer was observed with a 1.5 T clinical magnetic resonance (MR) imaging system. The magnetization transfer ratio of chemically skinned (calcium-sensitive) muscle fiber preparations increased much more in a rigor state than in a relaxed state, while that of calcium-insensitive fiber preparations and solutions showed no difference. These results suggest that the formation of actomyosin complexes increased the magnetization transfer ratio. A clinical MR system is not only effective for medical imaging, but also has the potential to demonstrate physiological characteristics.

Effects of muscular contraction on discharge patterns of neurons in the medullary raphe nuclei

Cells of the medullary raphe nuclei were characterized as sympathoinhibitory (SI), sympathoexcitatory (SE) or serotonergic (5-HT). When muscular contraction (MC) was evoked by stimulation of the L 7 and S 1 ventral roots, putative SI cells were inhibited while putative SE cells were excited. 5-HT cells were unaffected by MC. These data are discussed in relation to integration of somatosensory and cardiovascular reflexes.

Diameter changes in arteriolar networks of contracting skeletal muscle

The effect of muscular contraction on vessel diameter was studied in the arteriolar network of the exteriorized cat sartorius muscle during normal and elevated vascular tone. Dilation during 4 Hz motor-nerve stimulation was proportionately greatest in the third-order (transverse) arterioles and in vessels immediately upstream and downstream (P less than 0.01). This pattern of dilation was maintained with increased contraction frequency (30 Hz) and during concurrent sympathetic nerve stimulation (8 Hz). The pattern of constriction with sympathetic nerve stimulation alone showed a similar trend with the greatest response in the third-order and adjacent vessels. A model developed to estimate the resistance distribution in the arteriolar network, using data from earlier micropressure and vascular architecture studies in the sartorius muscle, allowed calculation of the resistance change during muscle contraction and sympathetic stimulation. Model predictions indicate that the third-order and adjacent vessels are the greatest site of resistance with both normal and elevated vascular tone. Thus these vessels were the site of greatest resistance change during muscle contraction. The more proximal, arcade vessels made lesser contributions to overall resistance changes, whereas the most distal, fifth-, and sixth-order arterioles appear not to be important in this regard. These findings indicate the third-order, transverse, arterioles are of special importance in regulating blood flow in the sartorius muscle.

Cineradiogrphic analysis of eustachian tube function. Experimental study.

In order to determine the effect of muscular contraction upon the opening processes of the eustachian tube, cineradiography of four monkeys' tubes during stimulation of the tensor and levator veli palatini muscles was carried out. Levator stimulation produced no opening of the tube except a dilation of the pharyngeal orifice. On the other hand, tensor stimulation produced a consistent opening of the tube by outward displacement of the tubal wall along its entire cartilaginous part. A marked time lag in the movement of the tube between its proximal (isthmic) and distal (pharyngeal) parts was regarded to be important in the clearance function of the tube.

Effect of muscular contraction on cholesterol oxidation.

ARTICLESEffect of muscular contraction on cholesterol oxidationM. R. Malinow, P. McLaughlin, and A. PerleyM. R. Malinow, P. McLaughlin, and A. PerleyPublished Online:01 Dec 1968https://doi.org/10.1152/jappl.1968.25.6.733MoreSectionsPDF (641 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByEffects of Training and Detraining on the Distribution of Cholesterol, Triglyceride, and Nitrogen in Tissues of Albino RatsCirculation Research, Vol. 31, No. 6 More from this issue > Volume 25Issue 6December 1968Pages 733-735 Copyright & PermissionsCopyright © 1968 the American Physiological Societyhttps://doi.org/10.1152/jappl.1968.25.6.733PubMed4973252History Published online 1 December 1968 Published in print 1 December 1968 Metrics

THE INFLUENCE OF ELECTROCONVULSIVE TREATMENT ON BLOOD SUGAR, TOTAL NUMBER OF LEUCOCYTES AND LYMPHOCYTES

The changes in blood sugar level, leucocyte count, and absolute lymphocyte count were studied in patients undergoing electric shock therapy. The blood sugar and white blood cell response to the injection of adrenalin was observed in 4 subjects. In all cases electric shock was associated with leucocytosis and lymphocytosis, and in the majority of cases (28 out of 34) a hyperglycemia was observed. The values returned to normal within an hour of treatment. On mathematical evaluation the findings were seen to be statistically significant. The type of response was not correlated to the underlying psychiatric conditions; where a series of treatments was followed in one single individual, the pattern of response was maintained throughout, irrespective of change in the psychiatric condition of the patient. The hyperglycemia appeared to be the result of autonomic stimulation, while the leucocytosis and lymphocytosis seemed due, at least in part, to the mechanical effect of muscular contraction.

The effect of muscular contraction upon the blood flow in the skeletal muscle, in the diaphragm and in the small intestine

In the previous communication, p. 233, experiments were described dealing with the effect of contraction of the skeletal muscle upon its blood flow. Short and prolonged tetanic contractions were evoked in various skeletal muscles by stimulation of their cut or uncut motor nerve or by direct stimulation of the muscle. Stimulation of the motor nerve as well as that of the muscle ma involve to an unknown extent the vasomotor innervation of the respective muscles and, although strong evidence was provided that none of the effects observed were even in part due to a direct excitation of the vasomotor fibres, we thought it necessary to repeat our experiments under conditions in which direct excitation of vasomotor fibres is definitely avoided. The present communication describes experiments on the reflex contraction of the tibialis and of the quadriceps femoris (vastocrureus) muscles. So far as we are aware, there is only one reference in the literature which related to circulatory conditions in muscles during a reflex contraction. Denny-Brown (1929), by direct microsopical observations of the surface of the soleus muscle during a stretch reflex, noticed that even a modest amount of pull on the tendon opens up numerous capillaries and hastens the flow of blood in them to a remarkable extent. The tension developed was sometimes as great as 1∙5 kg. Weight. As a result of this observation, Denny-Brown believes that the capillaries are not compressed by the muscle fibres when these contract reflexly. It is, however, quite likely that the circulatory conditions in the superficial layers of the muscle differ from those in the depth of the muscle. Moreover, it is extremely difficult to remove completely all the connective tissue from the surface of the muscle, and we know from Rein's experiments (Keller, Loeser, and Rein, 1930), as well as from our own previous experiments (Anrep, Blalock, and Samaan, 1933), that during the contraction of a muscle there may be considerable dilatation in the resting tissues. In order to determine the total arterial inflow into the tibialis anticus during its reflex contraction, we performed experiments which were similar to those described in our previous communication.

The effect of muscular contraction upon the blood flow in the skeletal muscle

The successful application of the hot wire anemometer to the study of the coronary circulation (see Anrep, Davis, and Volhard, 1931) incited us to use the same method in a series of experiments upon the circulation in the skeletal muscle. Until recently, the blood flow through muscles was measured either by direct observation of the outflow of blood from a cut muscle-vein or with the help of various mechanical "Stromuhrs" (Sczelkow, 1863; Ludwig and Schmidt, 1868; Sadler, 1869; Gaskell, 1877). These methods allowed only a coarse registration of average blood flows in comparatively long intervals of bearing upon the problem. According to Gaskell, there is a large increase in the venous outflow from the muscle at the beginning of a tetanic contraction; with the continuation of the tetanus, the outflow is rapidly and greatly diminished and frequently it even stops; after the end of the tetanus, the outflow again increases decidedly above normal, and returns to the normal level only after a considerable interval of time. Gaskell considered that the initial increase and the subsequent diminution of the venous outflow during the tetanus was due to a mechanical diminution of the venous outflow during the tetanus was due to a mechanical compression of the blood vessels. The large increase, which he observed as an after-effect of the tetanus, he regarded as due to the action of potent vasodilator chemical substances which accumulated within the muscle during its contraction. A more exact determination of the time relations between the contraction and the changes in the venous outflow from the muscle has been attempted by Burton-Opitz (1903) with the help of Hürtle's Stromuhr. His experiments confirmed the observations of Gaskell, except that he failed to observe the prolonged increase of the blood flow after the termination of the tetanus. He described only a small outrush of blood immediately following the relaxation; this increase in the flow lasted, however, only a 1/2 to 1 second. On comparing the blood flow during tetanus, or during a series of single contractions with the resting blood flow, Burton-Opitz found a considerable decrease in the first case and an increase in the second. Unlike Gaskell, he ascribes both effects the tetanus, and to a massaging action of the single contractions. In the latter case, the increase of the blood flow was found to be roughly proportional to the volume of blood expelled from the muscle during each contraction. Verziar (1912) also observed an arrest of the venous outflow during each tetanic contraction.