Activation of sustained sympathetic vasodilatation in dog by spinal cord stimulation

Summary Electrical stimulation in lateral sites of the upper cervical spinal cord evoked vasodilatation after adrenergic blockade. Sympathetic fibres mediating sustained vasodilatation were shown to be separate from adrenergic sympathetic fibres since the adrenergic vasoconstrictor response in the paw evoked by vasomotor stimulation in the medulla was not reversed to vasodilatation after bretylium.Supported by USPHS Grant No. HL 08570 and part of thesis work by Dr.Rolewicz.     

A new stimulation technique of the crista ampullaris of the lateral canal in the adult cat: study of the action potential of the vestibular nerve.

The stimulation of the crista ampullaris of the lateral canal by a short ampullopetal liquid flux produces on the pre-ganglionic vestibular fibres the appearance of a bimodal action potential. The amplitude of this action potential increases with the intensity of the stimulation. This stimulation also provokes the birth of an evoked potential at the level of the vestibular nuclei as well as an ocular jerk.     

The effect of Apamin® on nonadrenergic,noncholinergic nervous vasodilatations in the cat small intestine

Summary The intestinal vasodilation evoked by mechanical mucosal stimulation or by transmural electrical field stimulation was abolished by close i.a. injection of Apamin, a polypeptide originally isolated from bee venom. Apamin also blocked the vasodilatation induced by close i.a. infusion of vasoactive intestinal polypeptide (VIP). It is suggested that Apamin is a VIP receptor antagonist.This research was sponsored by grants from the Swedish Medical Research Council (14X-2855), from the Swedish Society for Medical Sciences, from Magnus Bergvalls Stiftelse and from the Medical Faculty, University of Göteborg.     

A new stimulation technique of the crista ampullaris of the lateral canal in the adult cat: Study of the action potential of the vestibular nerve

Summary The stimulation of the crista ampullaris of the lateral canal by a short ampullopetal liquid flux produces on the pre-ganglionic vestibular fibres the appearance of a bimodal action potential. The amplitude of this action potential increases with the intensity of the stimulation. This stimulation also provokes the birth of an evoked potential at the level of the vestibular nuclei as well as an ocular jerk.Supported by the D.G.R.S.T. grant 77.7.0669 and I.N.S.E.R.M. (A.S.R. No. 6, grant 011).     

Pathways for excitatory and inhibitory innervation to the guinea-pig tracheal smooth muscle.

The trachea receives excitatory cholinergic innervation from the vagus nerve and the stellate ganglion. Inhibitory adrenergic fibres have the same sources. Those in the vagus nerve probably derive from high vagosympathetic anastomoses. Nonadrenergic inhibitory fibres have a preganglionic vagal supply.     

Prostaglandin E2 increases mechanically evoked potentials in the peripheral nerve

Summary Subdermal injections of PGE₂ (5 g) in the rat foot lead to increases in the potentials evoked in sensory nerve branches by the mechanical stimulation of the skin. This sensitization of both A and C fibres complements the previously described hyperalgesic effects of prostaglandins of the E series.     

Pathways for excitatory and inhibitory innervation to the guinea-pig tracheal smooth muscle

Summary The trachea receives excitatory cholinergic innervation from the vagus nerve and the stellate ganglion. Inhibitory adrenergic fibres have the same sources. Those in the vagus nerve probably derive from high vagosympathetic anastomoses. Nonadrenergic inhibitory fibres have a preganglionic vagal supply.This study has been supported by grants from Magnus Bergvall Memorial Found and Harald and Greta Jeansson Foundation.     

Comparison of the responsiveness of isolated arteries and veins taken from the same dogs 17 days apart

Summary The present experiments demonstrate that isolated arteries and veins taken from the same dogs before and after an interval of 17 days show comparable responses to adrenergic nerve stimulation, exogenous norepinephrine and depolarizing solution. They provide an acceptable model for the in vitro study of chronic influences on canine vascular responsiveness.     

Leukocyte mobilization from the guinea pig spleen by muscarinic cholinergic stimulation

Important interactions between the immune system and the nervous and endocrine systems have become increasingly accepted. The present results demonstrate that the cholinergic agonist carbacholine greatly increased the number of granulocytes and lymphocytes in the splenic venous blood, but not arterial blood, shortly after administration to guinea pigs. The effect was largely blocked by pretreatment with atropine. In contrast, animals treated with indomethacin had a decreased number of leukocytes in both splenic venous and arterial blood. A decrease in relative splenic weight due to carbacholine treatment was also blocked by atropine. However, cholinergic leukocyte mobilization, or that previously observed after adrenergic stimulation, may not be caused by capsule contraction since it is not accompanied by mobilization of erythrocytes. Furthermore, indomethacin, which potentiates the response of splenic smooth muscle to adrenergic stimuli, blocked the effect of noradrenaline (NA) on leukocyte mobilization.     

Leukocyte mobilization from the guinea pig spleen by muscarinic cholinergic stimulation

Important interactions between the immune system and the nervous and endocrine systems have become increasingly accepted. The present results demonstrate that the cholinergic agonist carbacholine greatly increased the number of granulocytes and lymphocytes in the splenic venous blood, but not arterial blood, shortly after administration to guinea pigs. The effect was largely blocked by pretreatment with atropine. In contrast, animals treated with indomethacin had a decreased number of leukocytes in both splenic venous and arterial blood. A decrease in relative splenic weight due to carbacholine treatment was also blocked by atropine. However, cholinergic leukocyte mobilization, or that previously observed after adrenergic stimulation, may not be caused by capsule contraction since it is not accompanied by mobilization of erythrocytes. Furthermore, indomethacin, which potentiates the response of splenic smooth muscle to adrenergic stimuli, blocked the effect of noradrenaline (NA) on leukocyte mobilization.     

Pharmacology and function of the myoepithelial cell in the eccrine sweat gland.

Both acetylcholine and a Ca-ionophore, A23187, are comparatively strong stimulants of eccrine sweat secretion in vitro. Nevertheless, the contraction of the secretory coil was seen only after stimulation with acetylcholine but not with alpha or beta adrenergic drugs or with A23187. It was thus inferred that the myoepithelial contraction may not be playing an indispensable role in the overall process of eccrine sweat secretion.     

Antidromic responses evoked in the central end of the phrenic nerve by stimulation of the ipsilateral dorsal column in the cat]

In 15 adult cats under nembutal anaesthesia the dorsal columns have been stimulated at the level of the first and the second cervical segments. Under these conditions antidromically evoked responses appear both on the ipsilateral radial and phrenic nerves. Some of the afferent phrenic fibres thus activated may be related to the diaphragm muscle receptors. In some experiments a group of thin fibres (conduction velocity comprised between 16-20 m/sec) were also activated.     

Altered adrenergic responses of the coronary arterial bed in alloxan-diabetic dogs

Summary The conductivity of the coronary arterial bed increased in healthy and decreased in alloxan-diabetic dogs in response to intracoronary administration of norepinephrine or sympathetic stimulation. This suggests a modification of adrenergic receptors sensitivity in diabetes.     

Pharmacology and function of the myoepithelial cell in the eccrine sweat gland

Summary Both acetylcholine and a Ca-ionophore, A23187, are comparatively strong stimulants of eccrine sweat secretion in vitro. Nevertheless, the contraction of the secretory coil was seen only after stimulation with acetylcholine but not with alpha or beta adrenergic drugs or with A23187. It was thus inferred that the myoepithelial contraction may not be playing an indispensable role in the overall process of eccrine sweat secretion.Acknowledgment. The present study was supported by NIH grant 2R01AM 1625804.     

A promoting action of cyclic GMP on contractions of guinea-pig vas deferens.

The effect of dbc-GMP has been studied in ductus deferens of the guinea-pig. The nucleotide potentiated the contractions induced by electrical field stimulation and by adrenergic agonists. The site of action was probably in the smooth muscle cell, since the release of excitatory transmittor was not influenced.     

Relation of the character of capacitance vessel responses in spleen and small intestine elicited by electrical stimulation of the sympathetic fibres to the level of oxygen exchange in the organs

Summary There is a correlation between character and magnitude of capacitance vessel responses and venous blood oxygen saturation under electrical stimulation of sympathetic fibres in the spleen and small intestine.     

Birefringence signals and tension development in single frog muscle fibres at short stimulus intervals.

The early large birefringence signal and mechanical activity were studied together in isolated single fibres of frog skeletal muscle with double stimulation at short stimulus intervals (2-60 msec) at room temperature and at 4--6 degrees C. In all fibres tested, extra tension and additional birefringence signal in response to the second stimulus appeared simultaneously and suddenly upon increasing the stimulus interval. The shape of the stimulus-interval versus tension-development curve makes it highly improbable that subthreshold calcium release occurs at shorter stimulus intervals; therefore, tension development reliably reflects Ca-release in these experiments. In contrast to the report by Suarez-Kurtz and Partker, birefringence signal and calcium release are shown not to be dissociated by double stimulation. This result supports the hypothesis that the early large birefringence signal is an intrinsic indicator of calcium release from the sr during EC-coupling in skeletal muscle.     

Birefringence signals and tension development in single frog muscle fibres at short stimulus intervals

Summary The early large birefringence signal and mechanical activity were studied together in isolated single fibres of frog skeletal muscle with double stimulation at short stimulus intervals (2–60 msec) at room temperature and at 4–6°C. In all fibres tested, extra tension and additional birefringence signal in response to the second stimulus appeared simultaneously and suddenly upon increasing the stimulus interval. The shape of the stimulus-interval versus tension-development curve makes it highly improbable that subthreshold calcium release occurs at shorter stimulus intervals; therefore, tension development reliably reflects Ca-release in these experiments. In contrast to the report by Suarez-Kurtz and Parker, birefringence signal and calcium release are shown not to be dissociated by double stimulation. This result supports the hypothesis that the early large birefringence signal is an intrinsic indicator of calcium release from the sr during EC-coupling in skeletal muscle.     

Influence of cervical sympathetic nerve stimulation on carotid sinus baroreceptor afferents

Summary In rabbits and dogs, the response of low-threshold carotid sinus baroreceptor afferent fibres to cervical sympathetic nerve stimulation at various non-pulsatile steady pressures was examined. Fibres which possessed a rhythmic bursting discharge at low pressures increased this activity during sympathetic stimulation; all other low-threshold afferents were unaffected.This work was supported by the Medical Research Council of Canada and the British Columbia Heart Foundation.     

Ricerche fisiologiche sulla distribuzione periferica del nervo depressore aortico destro nel cane

Summary The periferal distribution of the right aortic nerve has been studied in physiological experiments on the dog. It has been found that after section of both Hering's nerves and left vago-depressor trunk and after denervation of the baroceptor area ofMuratori-Nonidez lying at the root of the right subclavian artery, the electrical stimulation of one splancnic nerve or the intravenous injection of adrenaline still produces a reflex bradycardia; moreover the cooling of the vagus nerve still results in a rise of the blood pressure. It is inferred that a group of baroceptor fibres of the right aortic nerve originate from areas situated in the aortic region.