摘要:

AbstractLeft ventricular receptors, signalling in non‐medullated vagal fibres and displaying a low, irregular spontaneous activity, have been analysed by recordings of impulse activity in cardiac afferent nerves. The receptors were distributed diffusely all over the ventricle and in both superficial and deep layers of the myocardium. They were activated by occlusions of the ascending aorta, by substantial elevations of arterial blood pressure and by rapid infusions of saline or dextran, whenever these procedures produced a clearcut increase of intraventricular diastolic pressure and end‐diastolic volume. The endings were also excited by veratrum alkaloids, nicotine and digitalis alkaloids. When activated, the receptors usually displayed a cardiac rhytm, but with intense stimulation the activity usually became continuous. The receptors evidently function as mechano‐ or deformation receptors, responding primarily to a distension of the ventricle. Activation of the receptors causes a reflex bradycardia and, in all probability, vasodilatation and blood pressure fall. They may contribute to the homeostatic control of blood pressure and blood volume, but their main function seems to be to protect the heart frome.g. imminent overloading. The endings are probably of main importance for the emergence of the Bezold‐Jarisch

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05246.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractImpulse activity in vagal afferent fibres and changes in heart rate were simultaneously recorded during rapid hemorrhage or blood pooling in cats in order to elucidate whether the sudden reflex bradycardia, sometimes evoked with the mentioned interventions, was correlated to an increased activity in any type of heart receptors. The results show that the slowing of the heart, resulting from an emptying of the central blood reservoirs was correlated to, and preceded by, an increased activity in receptors located in the left ventricle and signalling in non‐medullated afferents. The receptors were found to be activated also by obstructions of the ascending aorta and mechanical stimulation of the heart, and therefore seem to operate as mechanorecepton, stimulated by a “distortion” of the myocardium. ‐ It is conceivable that with rapid bleeding or pooling of blood, the receptors are excited by an improper squeezing of the myocardium when the ventricles contract vigorously around an almost empty chamber, and then induce a reflex bradycardia. This reflex mechanism, resembling the so‐called vaso‐vagal syncope reaction in man, may therefore serve as a protective system causing a break on the heart and allowing for an improved diastolic filling in situations when venous return is critica

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05247.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractIn order to study the influence of deep barbiturate anesthesia upon the regulation of extra‐ and intracellular pH in the brain, hypercapnia was induced in rats anesthetized for maximally three hrs with either 200–250 mg/kg of phenobarbital, or with 0.6 % halothane. There were no differences in the regulation of the CSF pH between the groups studied. However, both at 15 min at and 3 h the phenobarbital anesthesia was associated with a less efficient regulation of the intracellular pH'. At 15 min the regulation observed came close to that expected on the basis of pure physicochemical buffering. It is concluded that deep phenobarbital anesthesia, probably due to its effect on metabolism, can interfere with the mechanisms which regulate intracellular pH' during hypercap

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05248.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe response in the facial nucleus to stimulation of peripheral facial and trigeminal nerve branches is described. After antidromic invasion the excitability of facial motoneurons was lowered for up to 30 ms before as well as after intravenous injections of strychnine. The depression following antidromic stimuli is thus not caused by postsynaptic inhibition of the Renshaw type but rather by positive afterpotentials in the motoneurons. Synaptic activation by tap stimulation of the face led to increased motoneuron excitability setting in after a latency of 3 ms and lasting for 30 ms. This was followed by a lowered excitability lasting for an additional period of 65 ms. The period of depression was presumed to be due to postsynaptic inhibition of motoneurons. The changes of the excitability of facial motoneurons following synaptic activation explain in part previously observed effects of conditioning afferent stimuli on facial reflexes.‐Responses to electrical stimulation of facial and hypoglossal nerve afferents were recorded from reticular neurons. These neurons responded to single stimuli with a repetitive high‐frequency discharge related to the stimulus strength and could respond to an afferent inflow from large areas of the body and limbs. It is discussed whether these reticular neurons may be interneurons in a system exerting inhibitory control of facial muscle refle

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05249.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe intracranial pressure, measured as the ventricular fluid pressure, was recorded continuously during about 2 days in conscious rabbits at various time‐periods after bilateral decentralization (preganglionic denervation) of the superior cervical sympathetic ganglia. The pressure recorded 5 h after the operation was initially unchanged compared with non‐denervated control animals. During the following day it increased by approximately 50 mm physiological saline. The pressure was elevated (by approximately 25 mm saline) also 6 days after the operation. At 2 weeks it had returned to almost the same level as in the non‐denervated controls. It is suggested that the alterations in the ventricular fluid pressure mainly reflect changes in the cerebral blood volume, although direct effects on the sympathetically supplied choroid plexuses cannot be exc

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05250.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractChanges in the noradrenaline concentration of the sympathetically innervated pial vessels, choroid plexuses, and irides of the rabbit were measured fluorometrically at various periods during the first 2 weeks after pre‐ or postganglionic denemation (decentralization or excision of the superior cervical ganglia). The noradrenaline values fell to negligible amounts within 2 days after ganglionectomy in all organs, probably somewhat slower in choroid plexuses. After decentralization the noradrenaline level increased in the pial vessels, whereas in the choroid plexuses and iris it initially decreased followed by normalization. The fall occurred somewhat later in the iris. It is suggested that the results of the denervation experiments reflects the presence of functionally different types of sympathetic neurons in one and the same ganglio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05251.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe hemodynamic responses to hypothermia and shivering were investigated in 4 relaxed, in 9 deeply anesthetized and 9 lightly anesthetized new‐born lambs. Muscle‐relaxation and deep anesthesia prevented the increases of the oxygen consumption and the cardiac output. In shivering lambs these parameters increased. Correction of metabolic acidosis increased temporarily the cardiac outputs. The cardiac responses to cold stress of the relaxed and deeply anesthetized lambs differed from that seen in the relaxed adult dogs but were similar to those observed in relaxed, β‐blocked dogs. This difference may be due to some kind of immaturity of the β‐adrenergic system in the new‐

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05252.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstract7 dogs were anesthetized only, ten dogs anesthetized and relaxed. Additionaly three dogs were anesthetized, relaxed and β‐blocked. All dogs were ventilated by oxygen. Hypothermia was produced by ice‐water immersion. The oxygen consumption decreased in all but the shivering group. Initially, the cardiac output increased in the shivering group, decreased in the β‐blocked group but an unexpected slight increase was observed in the relaxed group. The reason for this observation is being di

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05253.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractMonosaccharide permeability was studied in bovine mesenteric arteries and rabbit intestinal smooth muscle.14C‐labelled 3–0‐methylglucose was used to study counter‐transport and saturation kinetics. L‐glucose‐1–14C and D‐glucose‐1–14C were used to study substrate stereospecificity.14C and3H‐labelled sorbitol were used to estimate the extracellular space. In both bovine mesenteric arteries and smooth muscle from rabbit colon the membrane permeability of mono‐saccharides was characterized by substrate stereospecifici, ty, counter‐transport and saturation kinetics. Monosaccharides were transported down a concentration gradient. These results suggest that monosaccharides penetrate vascular and intestinal smooth muscle cell membranes by facilitated diffusion, In the concentration range 5.6–44.4 mM the distribution of unlabelled glucose in bovine mesenteric arteries corresponded to the distribu, tion of sorbitol‐14C, indicating that the membrane transport of glucose was rate limiting for the glucose metabolism. Insulin (0.1 U/ml) increased to a small degree the membrane transport of 3–0‐methylglucose in bovine mesenteric arteries. Compared with the effect of insulin on monosaccharide transport in skeletal muscle the effects on monosaccharide transport in bovine mesenteric arteries and rabbit co

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05254.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe perfusion pressure‐red cell flow relationship in the cortical and in the outer and inner medullary circulation has been investigated on 9 chloralos anesthetized mongrel dogs using an indicator‐dilution technique with 32‐P labelled red cells and internal detection with small needle‐shaped semiconductor detectors. The perfusion pressure was varied by a clamp on the aorta. High pressures were obtained by ligation of the carotid arteries and section of the vagal nerves preceded by denervation of the renal nerves. The change in red cell flow on changing the perfusion pressure was determined from 1. the change in the regional mean transit time and 2. the change in regional red cell volume. The flow in all the regions studied was then found to be lineary related to the perfusion pressure up to some 70 mm Hg, whereas in the pressure range between 70 and 200 mm Hg it remained essentially unchanged. The findings indicate an autoregulative response in both the cortical and medullary circ

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1972.tb05255.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY