关键词： rapidly acting arterial pressure control system   open-loop gain   hemorrhage infusion   conscious rabbit  

摘要： The responsiveness of the rapidly acting arterial pressure control system to hemorrhage and infusion was investigated. Two catheters, one for pressure measurement and the other for inducing hemorrhage and infusion, were chronically implanted in 19 rabbits. A few days after the operation, each animal was quickly bled and transfused (2 ml/kg body wt) at intervals of 5 min while it was conscious. The hemorrhage-infusion experiment was repeated 16 times in each animal. The 16 strings of data were pooled for each animal. The overall open-loop gains (G) of the rapidly acting arterial pressure control system were estimated from the individually pooled responses to hemorrhage and infusion. There was no significant difference between the G-values, i.e., 7.2 .+-. 1.2 by hemorrhage and 7.1 .+-. 1.2 by infusion (mean .+-. SD), as evaluated by the paired t-test (P > 0.5). Thus, the responsiveness of the rapidly acting arterial pressure control system to quick mild hemorrhage and to infusion appears to be similar.

关键词： Baroreflex   Myocardial contractility   Hypertension sympathetic   Vagus   Peak LVdP/dt   Mean arterial pressure   Autonomic effectors  

摘要： The relative roles of vagal and sympathetic effector mechanisms in the baroreflex control of myocardial contractility were assessed in the conscious normotensive and hypertensive rabbit. Graded increases in mean arterial pressure (MAP) were produced by inflation of a balloon occluder around the abdominal aorta. Stimulus response curves relating the change in MAP to the induced change in peak rate of change of left ventricular pressure (peak LV dP/dt) were produced when heart rate was allowed to change and when it was held constant by atrial pacing. These curves were repeated after sympathetic blockade with propranolol, vagal blockade with methylscopolamine and combined blockade with the 2 drugs together. Increase in MAP produced a reflex fall in peak LV dP/dt which was due to 2 components. There was a reflex negative inotropic effect which was independent of heart rate, occurring n animals in whom heart rate was held constant by atrial pacing, and there was also a reduction in peak LV dP/dt which was caused by the reflex bradycardia when the heart rate was allowed to change. Both sympathetic and vagal efferents contributed to the reflex fall in peak LV dP/dt seen after elevation of MAP, the sympathetic being primarily responsible for the direct negative inotropic effect and the vagus for the bradycardia and hence the secondary effects on peak LV dP/dt. The slope of the stimulus response curves relating the fall in peak LV dP/dt to the increase in MAP was similar in intact normotensive and hypertensive rabbits, both with and without atrial pacing. The sensitivity of the baroreceptor-myocardial contractility reflex was not impaired in the hypertensive animals, 6 wk after renal wrapping, even though reflex control of heart rate is blunted at this time. The relative contribution of the vagus and the sympathetic to the control of contractility was similar in normotensive and hypertensive animals when heart rate was allowed to change. When the heart rate was held constant

摘要： The effects Of 2 enkephalin analog, (D-Ala2, Met5) and (D-Ala2, D-Leu5) enkephalinamide, on gastrointestinal and colonic motility were investigated in conscious fasted and fed dogs using chronically implanted strain gauges. The drugs, abbreviated here with the names DALAMIDE and DADLE, respectively, were administered by using both the intracerebroventricular [i.c.v.] and i.v. routes at increasing doses. In fasted dogs when administered via the i.c.v. route at a dose of 20 ng .cntdot. kg, DALAMIDE disrupted the migrating myoelectric complex pattern. A similar effect was obtained with a dose 25 times higher (500 ng .cntdot. kg) administered i.v.;at this dosage DALAMIDE administered i.v. also reduced the colonic motility index by 66%. When i.c.v. administered in fed dogs, 2 h after a meal, DALAMIDE (20 ng .cntdot. kg) inhibited gastric motility complex pattern as ectopic complexes for 4-6 h. This effect was not reproduced by i.v. treatment even at the highest dose used (500 ng .cntdot. kg). Both i.c.v. and i.v. administration of DADLE, at doses as high as 100 and 500 ng .cntdot. kg, respectively, affected neither the motility pattern nor the motility index of the antrum and proximal jejunum in the fasted or fed state. I.c.v., but not i.v., administration produced a short (10-15 min) increase of colonic motility. Apparently, Met-enkephalin influences the gastrointestinal motility predominately by a central action, manifested as a migrating myoelectric complex reorganizing effect in fed dogs. Evidently, Leu-enkephalin exerts a predominately centrally mediated stimulation of colonic motility, whereas Met-enkephalin inhibits it probably by a peripheral mechanism.

关键词： Motor Activity   Hormonal Response   Motor Pattern   Distal Stomach   Complete Abolition  

摘要： The purpose of this study was to determine the hormonal response of the gastric motor activity to a meal. A conscious donor dog was used to perfuse an isolated canine stomach placed in a chamber, using a pump-oxygenator system for recirculation. Strain gauge transducers were used to record the motility of the isolated stomach. The donor dog was fed during the perfusion. An hour after the meal, the fed dog was replaced by a second fasted donor dog. Fasted motor activity in both the proximal and distal stomach was characterized by high-amplitude contractions occurring in bursts every 10 minutes. After feeding, there was complete abolition of high-amplitude contractions in the distal stomach in all 7 experiments. The proximal high-amplitude contractions were abolished in 5 experiments, but were still present in 2, although the contractile pattern was irregular. When the fed dog was replaced by a fasted dog, characteristic fasting motor patterns were resumed in the isolated stomach. There was a delay of up to 17 minutes in the onset of both the postprandial changes in motility and the reappearance of fasted motor patterns. The changes in the motility pattern of the isolated stomach after feeding the donor dog point to a hormonal response.

关键词： Y-Aminobutyric acid   dopamine   prolactin   tyrosine hydroxylase  

摘要： The present experiments were carried out to further elucidate the mechanism by which dopamine mediates the actions of Y-aminobutyric acid on prolactin release from anterior pituitary following its intraventricular injection in overiectomized conscious rats, Y-Aminobutyric acid significantly suppressed the prolactin levels at 0.1 Μmol concentration while at 4 Μmol dose, the level was elevated. The activity of tyrosine hydroxylase was increased significantly in the anterior pituitary at the lower dose while the higher concentration of Y-aminobutyric acid did not bring about any change in the activity both in the hypothalamus and the anterior pituitary. The results presented suggest that intracellular dopamine in the anterior pituitary may directly inhibit prolactin release; the plasma prolactin level is elevated by Y-aminobutyric acid, by way of either inhibiting dopaminergic tone or possible stimulation of a physiological prolactin releasin g hormone.

关键词： 印堂穴   功时   发功   仪器   头面部穴位   气功锻炼   穴位   意识  

摘要： 祖国医学宝库中的气功,有着几千年的悠久历史,几乎和中华民族的文化同时诞生,演变至今气功流派数以千计。不同流派由于锻炼方式不同,“外气”信号物理内容各异,即使是同一物理量其参数也各不相同,有静电荷富集及80%深度低频调制的红外辐射,有微粒流信号等,本文则报道当气功者程志久同志发功时,仪器对准他的印堂穴位,收到静电增量为10-14库仑量级,并测得电荷极性与练功方式有关。

摘要： The effect of synthetic motilin on contractile activity in the lower esophageal sphincter (LES) and the stomach was studied in 5 healthy dogs by means of chronically implanted strain gage force transducers. Motilin produced strong contractions in the LES and the stomach simultaneously after i.v. doses ranging from 0.3-2.7 .mu.g/kg h, which were similar to the naturally occurring interdigestive contractions in the LES and stomach. These contractions could be induced only in the interdigestive state;infusion of motilin into dogs in the digestive state brought about no significant effect on either the LES or the stomach. Motilin-induced contractions in the LES and the stomach were instantly abolished by ingestion of food. The contractions induced by motilin are identical with the naturally occurring interdigestive contractions in the LES and these contractions are the most orad component of the interdigestive cyclic recurring caudad-moving bands of strong contractions in the dogs.

关键词： Action Potentials   Adolescent   Adult   Electrodes, Implanted   Electrodes, Implanted   Feedback   Female   Humans   Male   Motor Neurons/physiology   Muscles/innervation   Neural Inhibition   Spinal Cord/physiology  

摘要： Multiple fine-wire electrodes were implanted in the biceps brachii of five subjects, and artificial electronic feedback was provided to subjects from only one electrode. By this technique, it was shown that neighboring units progressively stop firing as subjects concentrate on activating an isolated unit. The inhibition of neighboring spinal motoneurons in the same pool further indicates that selective inhibition is an automatic part of single motor-unit training.

关键词： ELECTROMYOGRAPHY   EQUIPMENT AND SUPPLIES   MOTOR NEURONS   NEUROPHYSIOLOGY   PERIPHERAL NERVES   SPINAL CORD