Source of intrinsic innervation of canine ventricles: a functional study

1987 ◽  
Vol 252 (3) ◽  
pp. H638-H644 ◽  
Author(s):  
T. M. Blomquist ◽  
D. V. Priola ◽  
A. M. Romero
Keyword(s):  
Cardiopulmonary Bypass ◽  
Ganglion Cells ◽  
Functional Study ◽  
Beta Blockade ◽  
Parasympathetic Innervation ◽  
Intrinsic Innervation ◽  
Series Of Experiments ◽  
Intrinsic Cardiac Nerves ◽  
Cardiac Nerves

Recently it has been suggested that the parasympathetic innervation of the ventricles is by way of postganglionic axones that emanate from ganglion cells in the atria, reaching the ventricles by traversing the atrioventricular (AV) groove. We designed a series of experiments to test this hypothesis. Phenol (89%) was applied to the AV groove and surrounding 5 mm of epicardium in 21 dogs on cardiopulmonary bypass. The effects of intracoronary acetylcholine (ACh; 1-5 micrograms) and intracoronary nicotine (NIC; 25–100 micrograms) on cardiac isovolumic pressures were evaluated after beta-blockade. In another series of experiments, eight dogs were exposed to phenol in the same way and allowed to recover for 7–10 days. Atrial and ventricular responses to NIC were unaffected by phenol application to the AV groove in the acute animals when compared with application of saline alone. However, in the chronic animals, pretreatment with phenol 7–10 days previously reduced the ventricular responses to NIC by 70% while leaving the atrial responses intact. These data indicate that the intrinsic cardiac nerves (ICN) of the canine ventricles consist primarily of postganglionic parasympathetic axones which arise from supraventricular ganglia and cross the AV groove.

Specification of retinotectal connexions during development of the toad Xenopus laevis

Development ◽  
1980 ◽  
Vol 55 (1) ◽  
pp. 77-92
Author(s):  
S. C. Sharma ◽  
J. G. Hollyfield
Keyword(s):  
Xenopus Laevis ◽  
Ganglion Cell ◽  
Retinal Ganglion Cells ◽  
Optic Tectum ◽  
Ganglion Cells ◽  
The Other ◽  
Retinal Ganglion ◽  
Visual Projection ◽  
Series Of Experiments ◽  
The Right

The specification of central connexions of retinal ganglion cells was studied in Xenopus laevis. In one series of experiments, the right eye primordium was rotated 180° at embryonic stages 24–32. In the other series, the left eye was transplanted into the right orbit, and vice versa, with either 0° or 180° rotation. After metamorphosis the visual projections from the operated eye to the contralateral optic tectum were mapped electrophysiologically and compared with the normal retinotectal map. In all cases the visual projection map was rotated through the same angle as was indicated by the position of the choroidal fissure. The left eye exchanged into the right orbit retained its original axes and projected to the contralateral tectum. These results suggest that retinal ganglion cell connexions are specified before stage 24.

Altered nicotinic sensitivity of AV node in surgically denervated canine hearts

1983 ◽  
Vol 245 (1) ◽  
pp. H27-H32
Author(s):  
D. V. Priola ◽  
M. B. Curtis ◽  
C. Anagnostelis ◽  
E. Martinez
Keyword(s):  
Fold Increase ◽  
Conduction Time ◽  
Mediating Effects ◽  
Extrinsic Denervation ◽  
Av Node ◽  
Intraventricular Conduction ◽  
Denervation Supersensitivity ◽  
Muscarinic Stimulation ◽  
Intrinsic Cardiac Nerves ◽  
Cardiac Nerves

The responses of normal and cardiac-denervated (DNV) dogs to acetylcholine (ACh) and nicotine (NIC) were examined to determine if the intrinsic cardiac nerves (ICN) that modulate electrical conduction display denervation supersensitivity. Control (n = 18) and DNV (n = 18) animals were placed on cardiopulmonary bypass. Recording of intra-atrial (P-A), intraventricular (H-V), and atrioventricular (AV) nodal (A-H) conduction times were made from the region of the His bundle. ACh (0.1-10 micrograms) was used to produce muscarinic stimulation, whereas NIC (0.1-400 micrograms) was employed to stimulate the ICN. All drugs were administered intracoronary. No supersensitivity to either ACh or NIC was seen in the data from the P-A or H-V intervals of the His electrogram in the DNV animals. However, this group displayed approximately a 10-fold increase in the negative dromotropic effect of NIC on the AV node compared with control. No significant change in muscarinic sensitivity of the AV node was observed in the DNV animals. We conclude that 1) no denervation supersensitivity of the ICN mediating effects on intra-atrial and intraventricular conduction occurs; 2) the AV node itself does not show muscarinic supersensitivity following extrinsic denervation; 3) the ICN do display denervation supersensitivity as shown by a 10-fold increase in the effects of NIC on AV nodal conduction time.

XXIII. The Croonian lecture.—On the rhythm of the heart of the frog, and on the nature of the action of the vagus nerve

1882 ◽  
Vol 173 ◽  
pp. 993-1033 ◽  
Keyword(s):  
Vagus Nerve ◽  
Ganglion Cells ◽  
Muscular Tissue ◽  
Relative Share ◽  
Cardiac Nerves

In all investigations upon the causation of the beat of the heart, one question stands forward prominently before all others, viz. : What is the relative share taken by the ganglion cells and the muscular tissue respectively in the production of its spontaneous rhythmical beats? And in any discussion upon the action of the cardiac nerves, the most important question always is, How far do they act on the ganglion cells, how far on the muscular tissue directly?

A quantitative analysis of the effects of excitatory neurotoxins on retinal ganglion cells in the chick

1990 ◽  
Vol 4 (3) ◽  
pp. 217-223 ◽  
Author(s):  
Ngoh Ngoh Tung ◽  
Ian G. Morgan ◽  
David Ehrlich
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Amacrine Cells ◽  
Small Cells ◽  
Retinal Ganglion ◽  
Chick Retina ◽  
Area 5 ◽  
Different Types ◽  
Displaced Amacrine Cells ◽  
Series Of Experiments

AbstractThe present study examines the differential effects of three excitotoxins, kainic acid (KA), N-methyl-D-aspartate (NMDA), and α-amino-2,3-amino-2,3-dihydro-5- methyl-3-oxo-4- isoxazolepropanoic acid (AMPA) on neurons within the genglion cell layer (GCL) of the chick retina. Two-day-old chicks were given a single, 5 μl, intravitreal injection of KA, NMDA, or AMPA at a range of doses. Following treatment with 40 nmol KA, there was a 21% loss of neurons in the GCL. At 200 nmol KA, the loss increased to 46%. Exposure to KA eliminated mainly small neurons of soma area 5–15μm2, and medium-sized ganglion cells of soma area 15–25μm2. Large ganglion cells (>25μ,2) remained unaffected. The vast majority of small cells were probably displaced amarcrine cells. At a does of 3000 nmol NMDA, no further loss of cells was evident. Exposure to 200 nmol AMPA resulted in a 30% loss of large and some medium-sized ganglion cells. In a further series of experiments, exposure to excitotoxin was followed by a retinal scratch, which eliminated retinal ganglion cells within the axotomized region. The results indicate that only a small proportion of displaced amacrine cells are destroyed by NMDA and AMPA, whereas virtually all displaced amarine cells are sensitive to KA. The findings of this study indicate the existence of subclasses of ganglion cells with specificity towards different types of excitatory amino acids (EAA).

The receptive field of the primate P retinal ganglion cell, II: Nonlinear dynamics

1997 ◽  
Vol 14 (1) ◽  
pp. 187-205 ◽  
Author(s):  
Ethan A. Benardete ◽  
Ehud Kaplan
Keyword(s):  
Receptive Field ◽  
Visual Processing ◽  
Ganglion Cells ◽  
Preceding Paper ◽  
Retinal Ganglion ◽  
First Order ◽  
Anatomy And Physiology ◽  
Series Of Experiments ◽  
A New Technique ◽  
P Cells

AbstractThe receptive-field properties of retinal ganglion cells (RGCs) provide information about early visual processing. In the primate retina, P cells form the largest class of RGCs (Rodieck, 1988). A detailed exploration of the dynamics of the two subdivisions of the P-cell receptive field—the center and the surround—was undertaken. In the preceding paper (Benardete & Kaplan, 1996), the first-order responses of the center and the surround of P cells were described, which were obtained with a new technique, the multiple m-sequence stimulus (Benardete & Victor, 1994). In this paper, the investigation of P-cell responses measured as S-potentials in the lateral geniculate nucleus (LGN) is continued, and significant nonlinear, second-order responses from the center and the surround are described. These responses are quantified by fitting a mathematical model, the linear-nonlinear-linear (LNL) model (Korenberg, 1973; Korenberg & Hunter, 1986; Victor, 1988) to the data. In a second series of experiments, demonstration that steady illumination of the surround modifies the gain of the center to contrast signals (see also Kaplan & Shapley, 1989) is made. In P ON cells, increasing the steady illumination of the surround decreases the gain and speeds up the center's first-order response. In P OFF cells, increasing the steady illumination of the surround increases the gain of the center while speeding up the response. The results of both sets of experiments are related to the known anatomy and physiology of the P cell.

Functional integrity of intrinsic cardiac nerves located over an acute transmural myocardial infarction

1987 ◽  
Vol 65 (1) ◽  
pp. 64-69 ◽  
Author(s):  
R. D. Janes ◽  
D. E. Johnstone ◽  
J. A. Armour
Keyword(s):  
Myocardial Infarction ◽  
Coronary Artery ◽  
Ventricular Fibrillation ◽  
Action Potentials ◽  
Blue Staining ◽  
C Fibers ◽  
Compound Action Potentials ◽  
Intrinsic Cardiac Nerves ◽  
Compound Action ◽  
Cardiac Nerves

Acute transmural myocardial infarction has been reported to functionally denervate the normal myocardium distal to the infarcted zone by interrupting neurotransmission in axons coursing in the subepicardial region of the myocardial necrosis. To directly investigate the viability of such neurotransmission, the effects of acute transmural myocardial infarction on conduction in the intrinsic cardiac nerves overlying and distal to an experimentally induced acute transmural myocardial infarction were studied. In eight dogs, during control states electrical stimulation of the epicardium adjacent to a coronary artery produced compound action potentials in the more cranially located cardiopulmonary nerves. Thereafter, in four dogs an acute transmural myocardial infarction was produced by injecting rapidly hardening latex into a major diagonal branch of the left anterior descending coronary artery. Epicardial stimulation over the infarct, as well as proximal or distal to it, produced compound action potentials that conducted at normal velocities for at least 12 h postinfarction. The transmural extent of the infarct was verified with tetrazolium blue staining at the end of the experiment. In the other four dogs, compound action potentials were generated in cardiopulmonary nerves as described above and then ventricular fibrillation was produced to assess the effects of global anoxia on the function of axons coursing in cardiac nerves. Following the onset of ventricular fibrillation, compound action potentials were generated in these nerves in C fibers for up to 2 h, in B fibers for up to 4 h, and in A fibers for at least 12 h. However, the conduction velocities of these axons was gradually reduced over these periods of time, indicating that, in contrast to the function of axons coursing over a transmural myocardial infarction, their function gradually deteriorated. Thus, by directly assessing the function of axons coursing over a transmural infarction, it is concluded that an acute transmural myocardial infarction does not significantly modify the function of intrinsic cardiac nerves coursing over such an infarct.

scholarly journals EXPERIMENTAL STUDY OF BONE REBUILDING IN THE PERIIMPLANTATION AREA UNDER IMMEDIATE LOADING ON DENTAL IMPLANTS

2021 ◽  
Vol 74 (4) ◽  
pp. 992-997
Author(s):  
Anatoliy M. Potapchuk ◽  
Yevhen L. Onipko ◽  
Vasyl M. Almashi ◽  
Ninel V. Dedukh ◽  
Oleksandr Ye. Kostenko
Keyword(s):  
Experimental Study ◽  
Functional Study ◽  
Immediate Loading ◽  
Implant Stability ◽  
Clinical Protocol ◽  
Functional Load ◽  
Series Of Experiments ◽  
The Difference ◽  
Definition Of ◽  
Immediate Implantation

The aim: Study of the dynamics of morphological rearrangement of bone under conditions of immediate occlusive functional load and the effect of splinting of implants with temporary orthopedic structures with the analysis of the coefficient of stability of implants during immediate implantation in the experiment. Materials and methods: A series of experiments was performed on 6 male Duroc pigs at the age of 6 months and weighing 40-60 kg. In the course of recent advances, the following methods have been used: the clinical protocol of immediate – implantation of time-consuming clothes, the definition of COEFICIENT, morphometry and light microscopy of the slides, statistical analysis. Results: By morphometric examination after 3 months the BIC in the series with splinting was 1.68 times higher compared to 1 month. studies, in a series of experiments without splinting – 1.9 times, after 3 months. the difference between implantation experiments with splinting components and without splinting is 1.6 times. During the functional study of the resonant – frequency analyzer, there is an increase in the ISQ in the second and third months after surgery, but this figure is higher in the study using the splint component. Conclusions: Stagnation of the shingle component in the case of intrinsic intraoperative functional juvenile implantation accelerates the dynamics of osteointegration, so that high indicators of the efficiency of the implant stability can be achieved.

Autonomic nervous system and cellular injury from circumflex ligation in dogs

1981 ◽  
Vol 240 (5) ◽  
pp. H738-H745 ◽  
Author(s):  
J. J. Elson ◽  
R. E. Ten Eick ◽  
D. H. Singer
Keyword(s):  
Neural Activity ◽  
Time Course ◽  
Sympathetic Nerves ◽  
Beta Blockade ◽  
Autonomic Nerves ◽  
Cellular Injury ◽  
Cross Sectional ◽  
Chronic Denervation ◽  
Cardiac Nerves

The role of the autonomic nerves in the development of irreversible cellular injury (ICI) after circumflex coronary occlusion was examined in dogs with intact, acutely, or chronically decentralized cardiac nerves. Cardiac nerves were chronically decentralized 2 wk before ligation (CD) or acutely at the time of ligation (AD). In one group of AD dogs, the beta-blocker oxprenolol (0.3 mg/kg) was administered before ligation (AD + Ox). Hearts were paced at 160 beats/min to exclude any contribution of rate change secondary to autonomic intervention. The results are expressed in terms of percent of the cross-sectional area of the posterior papillary muscle (PPM) sustaining ICI after 40-min occlusion: intact 64 +/- 4% (SE), 6 +/- 4%, AD 39 +/- 10%, and AD + Ox 2 +/- 2%. Both acute and chronic denervation protect against ICI even in the absence of changes in heart rate. Furthermore, in dogs with intact cardiac nerves, reduction in pacing rate from 160 to 60 beats/min also decreased the extent of ICI from 64 +/- 4 to 34 +/- 10%. Experiments defining the time course of development of ICI in the PPM indicate that protection was only temporary, delaying the onset of injury by 25 min. These findings suggest that 1) neural activity in extrinsic cardiac sympathetic nerves activate beta-receptors, thereby influencing the development of ICI, and 2) differences in protection afforded by acute denervation with and without beta-blockade indicated that intrinsic postganglionic sympathetic nerve terminals can liberate transmitter in response to ischemia even in the absence of extrinsic neural activity.

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