Fluorescence histochemical and electron-microscopical observations on the innervation of the atrial myocardium of the adult human heart

Human Pulmonary Vein Myocardial Sleeve Autonomic Neural Density and Cardiovascular Mortality

Myocardial sleeves around pulmonary veins (PVs) are highly innervated structures with heterogeneous morphological and electrophysiological characteristics. Autonomic nerve dysfunction in the myocardium may be associated with an increased risk of cardiovascular morbidity and mortality. This article studied autonomic neural remodeling in myocardial sleeves around PVs and atrial-PV ostia with immunohistochemical and morphometric methods with clinicopathological correlations. PVs were collected from 37 and atrial-PV ostia from 17 human autopsy hearts. Immunohistochemical analysis was performed using antibodies against tyrosine hydroxylase (TH), choline acetyltransferase (CHAT), and growth-associated protein 43 (GAP43). In the PV cohort, subjects with immediate cardiovascular cause of death had significantly decreased sympathetic nerve density in fibro-fatty tissue vs those with non-cardiovascular cause of death (1624.53 vs 2522.05 µm2/mm2, p=0.038). In the atrial-PV ostia cohort, parasympathetic nerve density in myocardial sleeves was significantly increased in subjects with underlying cardiovascular cause of death (19.48 µm2/mm2) than subjects with underlying non-cardiovascular cause of death with no parasympathetic nerves detected (p=0.034). Neural growth regionally varied in sympathetic nerves and was present in most of the parasympathetic nerves. Heterogeneous autonomic nerve distribution and growth around PVs and atrial-PV ostia might play a role in cardiovascular morbidity and mortality. No association in nerve density was found with atrial fibrillation.

P2 Receptors in Cardiac Myocyte Pathophysiology and Mechanotransduction

ATP is a major energy source in the mammalian cells, but it is an extracellular chemical messenger acting on P2 purinergic receptors. A line of evidence has shown that ATP is released from many different types of cells including neurons, endothelial cells, and muscle cells. In this review, we described the distribution of P2 receptor subtypes in the cardiac cells and their physiological and pathological roles in the heart. So far, the effects of external application of ATP or its analogues, and those of UTP on cardiac contractility and rhythm have been reported. In addition, specific genetic alterations and pharmacological agonists and antagonists have been adopted to discover specific roles of P2 receptor subtypes including P2X4-, P2X7-, P2Y2- and P2Y6-receptors in cardiac cells under physiological and pathological conditions. Accumulated data suggest that P2X4 receptors may play a beneficial role in cardiac muscle function, and that P2Y2- and P2Y6-receptors can induce cardiac fibrosis. Recent evidence further demonstrates P2Y1 receptor and P2X4 receptor as important mechanical signaling molecules to alter membrane potential and Ca²⁺ signaling in atrial myocytes and their uneven expression profile between right and left atrium.

Optimized protocol for immunostaining of experimental GFP-expressing and human hearts

Morphological and histochemical analysis of the heart is fundamental for the understanding of cardiac physiology and pathology. The accurate detection of different myocardial cell populations, as well as the high-resolution imaging of protein expression and distribution, within the diverse intracellular compartments, is essential for basic research on disease mechanisms and for the translatability of the results to human pathophysiology. While enormous progress has been made on the imaging hardware and methods and on biotechnological tools [e.g., use of green fluorescent protein (GFP), viral-mediated gene transduction] to investigate heart cell structure and function, most of the protocols to prepare heart tissue samples for analysis have remained almost identical for decades. We here provide a detailed description of a novel protocol of heart processing, tailored to the simultaneous detection of tissue morphology, immunofluorescence markers and native emission of fluorescent proteins (i.e., GFP). We compared a variety of procedures of fixation, antigen unmasking and tissue permeabilization, to identify the best combination for preservation of myocardial morphology and native GFP fluorescence, while simultaneously allowing detection of antibody staining toward sarcomeric, membrane, cytosolic and nuclear markers. Furthermore, with minimal variations, we implemented such protocol for the study of human heart samples, including those already fixed and stored with conventional procedures, in tissue archives or bio-banks. In conclusion, a procedure is here presented for the laboratory investigation of the heart, in both rodents and humans, which accrues from the same tissue section information that would normally require the time-consuming and tissue-wasting observation of multiple serial sections.

Peptidergic and catecholaminergic fibers in the human corneal epithelium. An immunohistochemical and electron microscopic study

Innervation of the clinically normal human corneal epithelium was investigated utilizing immunohistochemical and electron microscopic techniques. All corneal epithelial sheets examined demonstrated neuron specific enolase (NSE: a non-specific marker for neural elements), calcitonin gene-related peptide (CGRP: a putative marker for sensory fibers), and tyrosine hydroxylase (TH: a marker for catecholaminergic nerves) immunoreactive fibers. NSE, CGRP, and TH fibers formed a dense basal epithelial plexus. The CGrp fibers tended to have beaded profiles, while TH fibers were smooth. Numerous free nerve endings originating from the basal epithelial plexus og NSE and CGRP fibers terminated throughout the thickness of epithelium. The densities of fibers in the basal epithelial nerve plexus were: NSE greater than CGRP greater than TH. Transmission electron microscopy demonstrated two types of epithelial nerve fibers, one containing large dense-core vesicles and another small dense-core vesicles. Both types contained clear vesicles. These large and small dense-core vesicle fibers appeared to correspond to the CGRP and TH immunoreactive fibers, respectively. These results provide morphological baseline data on the normal sensory and sympathetic corneal epithelial innervation.

Myocardial catecholamines and their biosynthetic enzymes in various human heart diseases

Myocardial noradrenaline (NA) content, together with the activities of the enzymes tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) was measured in biopsy specimens taken during cardiac surgery from patients with various heart diseases. Fluorescence histochemical studies were also performed on comparable specimens. The mean NA content in patients with symptomatic ischaemic heart disease (IHD) was significantly higher than that in patients with valvular heart disease (VHD), atrial septal defect (ASD) or congestive heart failure (CHF). The lowest mean NA content was found in patients with CHF. The activities of TH and DBH were highest in the IHD group, although the differences between IHD and VHD groups were not significant. Histochemical investigations of adrenergic structures showed less fluorescence intensity in the CHF than in the other 3 groups. On the other hand, the density of the adrenergic nerve net and the size and number of varicosities were greatest in patients suffering from IHD. The significance of these results is discussed in relation to the pathophysiological mechanisms underlying these various disease conditions. In IHD the high myocardial NA content creates local conditions for excessive NA release into the myocardial interstitium at the onset of ischaemia, which is known to result in several adverse local consequences.

Morphology of human intracardiac nerves: an electron microscope study

Since many human heart diseases involve both the intrinsic cardiac neurons and nerves, their detailed normal ultrastructure was examined in material from autopsy cases without cardiac complications obtained no more than 8 h after death. Many intracardiac nerves were covered by epineurium, the thickness of which was related to nerve diameter. The perineurial sheath varied from nerve to nerve and, depending on nerve diameter, contained up to 12 layers of perineurial cells. The sheaths of the intracardiac nerves therefore become progressively attenuated during their course in the heart. The intraneural capillaries of the human heart differ from those in animals in possessing an increased number of endothelial cells. A proportion of the intraneural capillaries were fenestrated. The number of unmyelinated axons within unmyelinated nerve fibres was related to nerve diameter, thin cardiac nerves possessing fewer axons. The most distinctive feature was the presence of stacks of laminated Schwann cell processes unassociated with axons that were more frequent in older subjects. Most unmyelinated and myelinated nerve fibres showed normal ultrastructure, although a number of profiles displayed a variety of different axoplasmic contents. Collectively, the data provide baseline information on the normal structure of intracardiac nerves in healthy humans which may be useful for assessing the degree of nerve damage both in autonomic and sensory neuropathies in the human heart.

Distribution of purinergic P2X receptors in the rat heart

The distribution of P2X purinergic receptor subtypes has been determined in relation to nerve varicosities in the rat heart with immunohistochemistry. Large clusters (about 1 microm diameter) of co-localised and sometimes co-extensive P2X1 and P2X3 receptors were found at sites of tyrosine hydroxylase (TH) positive axon varicosities in the atrium and the ventricle. Varicosities that were labelled with antibodies to the synaptic vesicle epitope SV2 were frequently labelled also with antibodies to P2X3, P2X5 and P2X6 but not always with antibodies to P2X1. Especially prominent were large numbers of small clusters (about 400 nm diameter) of co-localised P2X2 and P2X5 receptors on the sarcolemma unrelated to nerves at all. During development the 1 day-old heart possessed an abundance of co-localised P2X2 and P2X5 small receptor clusters on the sarcolemma. These observations are discussed in relation to the role of purinergic receptors in the mammalian heart.

Changes in adrenergic nerves and tissue perfusion after freezing injury to the ear skin of rabbits

The aim of the present study was to investigate by a combined trypan blue and catecholamine fluorescence technique the sequential changes in cutaneous adrenergic nerves, the distribution of blood flow, and vascular permeability at the demarcation line that occurred after experimental cold injury. Nine New Zealand white rabbits weighing 4.0-4.4 kg had frostbite induced by pressing the bottom of a glass bottle 2 cm in diameter filled with liquid nitrogen against the shaved skin of the ear. All the rabbits were anaesthetised with ketamine hydrochloride (Ketamine) and xylazine hydrochloride (Rompun). Specimens were taken one and three days, and two weeks after frostbite. Control samples were taken from the opposite normal ear. Trypan blue was injected into a saphenous vein just before the specimens were taken. The specimens were always taken in the same way and selected so that the probable demarcation line of the frostbite ran across the middle. The glyoxylic acid-induced fluorescence method was used to show the adrenergic nerves. There were no adrenergic nerves around the vessels and no arteriovenous anastomoses in the central area of the injury after one day, but catecholamines had started to accumulate in the adrenergic nerve endings at the margins of the injured area. This accumulation was still more obvious three days after frostbite. Some fluorescent regenerating adrenergic nerves could already be seen at the probable demarcation line two weeks after frostbite. There was increased trypan blue fluorescence near the margin of the injured area after one day, indicating extravasation and vascular damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac noradrenergic nerve terminal abnormalities in dogs with experimental congestive heart failure

BACKGROUND

We have shown previously that norepinephrine (NE) uptake activity is reduced in the failing right ventricle of animals with right heart failure (RHF) produced by tricuspid avulsion and progressive pulmonary constriction. However, it is unknown whether this defect in neuronal NE uptake is related to reduction of noradrenergic nerve terminals or whether these changes also occur in animals with left heart failure (LHF). It is also unknown whether increased NE release in heart failure contributes to the noradrenergic nerve abnormalities.

METHODS AND RESULTS

We measured myocardial NE content. NE uptake function, and noradrenergic nerve profiles in dogs with either RHF or LHF induced by rapid ventricular pacing. NE uptake activity was measured using [3H]NE, and noradrenergic nerve profiles were visualized by glyoxylic acid (SPG)-induced histofluorescence and tyrosine hydroxylase immunocytochemical staining. To study the effects of excess NE, we exposed normal dogs to 8 weeks of chronic NE infusion using subcutaneous osmotic minipumps. RHF and LHF animals exhibited reduced myocardial contractile function and congestive heart failure, as evidence by reduced cardiac output and elevated right atrial pressure. However, unlike that in LHF, left atrial pressure was not increased in RHF. The animals also showed an increase in plasma NE and a decrease in cardiac NE. In addition, SPG-induced histofluorescence correlated significantly with NE uptake activity (r = .712, P < .001) and tyrosine hydroxylase immunoreactive profiles (r = .569, P < .001) in the right ventricles of RHF dogs and in both ventricles of LHF dogs. The numbers of catecholaminergic profiles and tyrosine hydroxylase profiles significantly correlated with cardiac filling pressures. Chronic infusion of NE decreased heart rate in normal dogs but had no effect on either mean aortic pressure or left atrial pressure; like heart failure, it resulted in significant decreases in myocardial NE uptake activity and numbers of SPG-induced catecholaminergic histofluorescence and immunoreactive tyrosine hydroxylase profiles.

CONCLUSIONS

Myocardial NE uptake activity was reduced only in the failing ventricles with elevated filling pressure in RHF and LHF. These changes probably were caused by loss of noradrenergic nerve terminals in the failing ventricles, as evidenced by the reductions of catecholaminergic histofluorescence and tyrosine hydroxylase immunostained profiles. Furthermore, since similar reductions of myocardial NE uptake and noradrenergic nerve profiles could be produced by chronic NE infusion in normal dogs, elevated NE levels may play a role in the development of cardiac noradrenergic nerve abnormalities in congestive heart failure.

Immunohistochemical and ultrastructural localisation of peptide-containing nerves and myocardial cells in the human atrial appendage

The innervation and myocardial cells of the human atrial appendage were investigated by means of immunocytochemical and ultrastructural techniques using both tissue sections and whole mount preparations. A dense innervation of the myocardium, blood vessels and endocardium was revealed with antisera to general neuronal (protein gene product 9.5 and synaptophysin) and Schwann cell markers (S-100). The majority of nerve fibres possessed neuropeptide Y immunoreactivity and were found associated with myocardial cells, around small arteries and arterioles at the adventitial-medial border and forming a plexus in the endocardium. Subpopulations of nerve fibres displayed immunoreactivity for vasoactive intestinal polypeptide, somatostatin, substance P and calcitonin gene-related peptide. In whole-mount preparations of endocardium, substance P and calcitonin gene-related peptide immunoreactivities were found to coexist in the same varicose nerve terminals. Ultrastructural studies revealed the presence of numerous varicose terminals associated with myocardial, vascular smooth muscle and endothelial cells. Neuropeptide Y immunoreactivity was localised to large electron-dense secretory vesicles in nerve terminals which also contained numerous small vesicles. Atrial natriuretic peptide immunoreactivity occurred exclusively in myocardial cells where it was localised to large secretory vesicles. The human atrial appendage comprises a neuroendocrine complex of peptide-containing nerves and myocardial cells producing ANP.

Neuritis cordis due to the acute polyneuritis of the Guillain-Barré syndrome

Three patients with the Guillain-Barré syndrome which followed the course of Landry's acute ascending paralysis died a sudden cardiac death. Autonomic dysfunction had appeared clinically, consisting of sphincter disturbances in one patient and fluctuating blood pressure and bradycardia in the other. In a twenty-three year old female patient cardiac function had been inconspicuous, apart from tachycardia, but the ECG showed S-T segment depression and flat T waves. Postmortem examination revealed acute inflammatory demyelinating polyradiculoneuritis involving the peripheral autonomic nervous system and especially the nerves of the heart. Immunohistochemically, the inflammatory cell infiltrations of this neuritis cordis consisted of macrophages (MAC 387 positive) and T lymphocytes (UCHL1 positive). No indication of a direct viral infection of the inflamed cardiac nerves was detectable by immunohistochemistry (HSV, CMV, influenza virus) nor by electron microscopy. The neuritis cordis was classified as an inflammatory cardio-neuropathy secondary to a patchy acute polyneuritis of the Guillain-Barré syndrome, involving the autonomic nervous system. Myocarditis could be discounted, and the neuritis cordis was thought to be responsible for the sudden cardiac death.

Congruence of adrenergic and cholinergic intrinsic innervation of human and rat atria

Right atrial biopsies from rat and human hearts were studied using combined methods for the demonstration of glyoxylic acid-induced fluorescence (GIF) of catecholamines and acetylcholinesterase (AChE) reactions in the same specimens. In specimens from the rat heart, the GIF and AChE reactions were performed either simultaneously or consecutively. In biopsies of the human right atrium, obtained at right atria cannulation during open-heart surgery, the reactions were performed consecutively. It was found that in both rat and human atria the adrenergic nerves and AChE reactive nerves, which are probably cholinergic, run partly separately and partly together. In the rat atrial specimens, close relations between adrenergic nerves and clusters of AChE reactive cells were observed. In addition, clusters of fluorescent cells were observed in the vicinity of AChE reactive nerve bundles. This indicates that there may be several possible means of peripheral interaction between the intrinsic adrenergic and cholinergic systems of the rat heart.

Light and electron microscopic demonstration of neuropeptide Y-like immunoreactive nerves in human cardiac muscle

Neuropeptide Y (NPY)-like immunoreactive nerves were demonstrated in human cardiac muscle. The atrial specimens were obtained from open-heart surgery. The PAP method was applied for immunocytochemistry for light and electron microscopy. A dense, extensive network of NPY-like immunoreactive nerve fibres was seen between cardiac muscle cells and around blood vessels. In electron microscope PAP precipitates were localized in large dense-cored vesicles of 80-120 nm in size in separate nerve terminals or in the terminals situated in the nerve bundles. Close contacts were observed between NPY nerves and muscle cells and blood vessels. The possible functional role of NPY innervation in the human heart is discussed.

The distribution of sympathetic nerve fibres in the AV node and AV bundle of the bovine heart

The sympathetic nervous system has important effects on the properties of the heart, including the conduction of the impulse. However, it is not known how this nervous system is distributed in the atrioventricular (AV) bundle, which together with the AV node constitutes the only conduction pathway between the atria and ventricles in normal hearts. Therefore, in the present study the adrenergic innervation in the bovine AV node/AV bundle was examined by use of the glyoxylic acid induced method for histofluorescence demonstration of catecholamines. Acetylcholinesterase (AChE) histochemistry was also used. It was found that the AChE-positive nerve fascicles in these regions partly contain sympathetic nerve fibres, that sympathetic nerve fibres occur in the proximity of some of the ganglionic cells that occur outside the AV node/AV bundle, that the arteries supplying AV bundle tissue as well as AV nodal tissue have perivascular plexuses of sympathetic nerve fibres, and that there is a substantial number of sympathetic nerve fibres outside Purkinje fibre bundle surfaces. The observations give new insight into the question of the distribution of the sympathetic nerves in the AV bundle in relation to the distribution of these nerves in the AV node. Possible functional implications of the observations are discussed.

Peptidergic innervation of human atrial myocardium: an electron microscopical and immunocytochemical study

Nerve terminals of human cardiac muscle were studied using an electron microscope. Substance P-, Leu-enkephalin- and vasoactive intestinal polypeptide-like (VIP) immunoreactive nerves were demonstrated by use of the light microscope. In addition, VIP- and substance P-like immunoreactive nerves were localized ultrastructurally by the peroxidase-antiperoxidase-method. Muscle specimens were obtained from right auricula of patients undergoing open-heart surgery. In the nerve fibres and terminals, which were situated close to the blood vessels and cardiac muscle cells several vesicle populations were identified. On the morphological basis the terminals could be tentatively categorized as cholinergic, mixed cholinergic-peptidergic, adrenergic, sensory or baroreceptor type, peptidergic and degenerating nerve endings. Substance P-, Leu-enkephalin- and VIP-like immunoreactive nerves were localized between cardiac muscle cells. Nerve terminals, which showed substance P-immunoreaction were observed also close to blood vessels. In substance P- and VIP-immunoreactive nerve terminals the immunoprecipitation was localized in large dense-cored vesicles of about 120 nm in diameter. It is concluded that the intrinsic control of the human heart is most probably regulated by several transmitter candidates. The peptidergic nerves may exert their modulatory interactions in the nerve bundles where they are situated close to each other but a direct effect on the blood vessels and muscle cells cannot be excluded.

Substance P- and leu-enkephalin-immunoreactive nerves before and after myocardial ischaemia, hypothermic chemical cardioplegia and reperfusion injury during open-heart surgery

During open-heart surgery, myocardial biopsies were obtained before the start of extracorporeal circulation (from the right auricular appendage) and after weaning from the pump (from the right atrium), and processed for immunocytochemical demonstration of substance P- and leu-enkephalin-immunoreactive nerve fibres and for electron microscopy. Substance P-immunoreactive nerves were seen around blood vessels, between myocardial cells and forming large glomerulus-like loops, but were not numerous. Leu-enkephalin-immunoreactive nerves were very sparse. We therefore believe that both nerve types primarily are modulatory axons. In the post-weaning specimens, nerves of both types were more numerous (attributable to the different site of biopsy), and no change was seen in the immunofluorescence reaction. The ultrastructure (all types) of nerve terminals was well preserved, although myocardial damage was obvious in many specimens. Cardiac nerves, including peptidergic nerves, thus seem to be relatively resistant to ischaemia, hypothermic chemical cardioplegia and reperfusion injury.

Adrenergic innervation of the human liver. A fluorescence histochemical analysis of clinical liver biopsy specimens

Liver biopsy specimens from 34 consecutive patients undergoing laparoscopy were processed for glyoxylic acid-induced fluorescence histochemical analysis. Most of the adrenergic nerves were located in the interlobular spaces and confined to blood vessels; no direct functional adrenergic innervation of the hepatocytes could be demonstrated. In eight cases of intrahepatic cholestasis, however, fluorescing varicose adrenergic axons were observed in patchy areas of accumulations of bile pigments. Otherwise the results were analogous in histologically normal liver tissue and in liver disease regardless of the underlying pathology. Methodological difficulties may explain some earlier contradictory results.

Multi-score estimation of catecholamine fluorescence for clinical purposes

Experience accumulated at multi-score semiquantitation of catecholamine fluorescence of glyoxylic acid-treated stretch preparations of human clinical specimens is presented. The methodology and criteria of quantitation are described in detail. For an example, comparison between 3 different methods for analyzing neural-bound noradrenaline in human myocardial tissue in various heart diseases (obtained during the course of cardiac surgery) is presented: Biochemical determination of tissue noradrenaline content multi-score estimation of catecholamine fluorescence of glyoxylic acid-treated stretch preparations microfluorimetric analysis of the same stretch preparations. The results show that the multi-score estimation method gives a reliable concept of the relative amounts of noradrenaline stored in the intrinsic adrenergic nerve net (corresponding closely to the individual and group differences observed at biochemical noradrenaline determination). In addition, possible regional differences, alterations in the structural integrity of the inbuilt intrinsic nerve net, and other structural changes (e.g. pathological catecholamine accumulations) are easily recognized, whereas biochemical estimation cannot give information on structural aspects, which may have important clinical repercussions. Microfluorimetry does not seem suitable for studies on human myocardial specimens for several reasons which are discussed. The method of multi-score estimation of catecholamine fluorescence described and discussed is recommended for other similar and related studies on human clinical materials.

Histochemical and ultrastructural study on the innervation of human and porcine atrio-ventricular valves

The presence of nerve fibers was investigated in porcine and human atrio-ventricular valves by AChE technique, formaldehyde-induced fluorescence, en bloc silver and gold chloride impregnation and electron microscopy. Elaborate nerve plexuses were observed in every leaflet and in some chordae tendineae of all the samples examined, without significant species differences in the pattern of innervation. The presence of a sensory innervation was inferred from the demonstration, in whole mount samples processed for acetylcholinesterase, of thick myelinated nerve fibers and of endings with dot-like or brush-like appearance. Moreover the results of the combined histochemical and ultrastructural methods showed the existence of both cholinergic and adrenergic efferent nerve fibers. Nerve varicosities with clear or dense-cored vesicles were frequently observed in proximity to blood vessels and to cardiac and smooth muscle bundles, which therefore can be considered as the targets of the efferent nerve supply. The complex pattern of the innervation herein demonstrated suggests the existence of a nervous control of valvular function through the regulation of contractile elements.

Myocardial catecholamines following cold cardioplegic arrest during open-heart surgery

Preservation of both right and left ventricular subendocardial and subepicardial muscle was assessed using quantitative polarization microscopy (birefringence measurements) with preservation of myocardial catecholamines measured by fluorescence microscopy in biopsies from 20 consecutive patients who underwent open heart surgery with cold cardioplegic arrest (St. Thomas' Solution). Six of the 7 patients with clinical complications were predicted from the birefringence results. One developed left ventricular deterioration during bypass, two patients right ventricular deterioration, one patient both left and right ventricular deterioration and two patients had poor left ventricular function before bypass. Birefringence measurements were thus reliable in predicting post-operative cardiac outcome. There were no significant changes during the bypass period in the catecholamine scores, even in those patients who had clinical complications. Fluorescence microscopy showed that the "free" myocardial nerve net and the pericoronary nerve plexuses retained their catecholamine stores equally well. This indicated that St. Thomas' cardioplegia preserves myocardial catecholamine stores, depletion of which would remove a potentially important compensatory mechanism in cardiac pump failure. There may however be a temporary blockade in the release of endogenous cardiac catecholamine (noradrenaline) stores from the adrenergic nerve terminals following cold cardioplegic arrest despite myocardial pump failure.

Fluorescence histochemical observations on the adrenergic innervation of the cardiovascular system in the aged rat

The Falck-Hillarp fluorescence technique was applied to tissue samples of the heart and certain vessels of both 4 and 24 month Wistar rats. It appeared that with increasing age, the density and fluorescence intensity of the cardiac sympathetic innervation was maintained at a level comparable to the young adult (4 month) in the atria, left ventricle and in the region of the sino-atrial node. Similarly the adrenergic innervation of the coronary vasculature, particularly in the atrium was maintained into old age. In contrast the adrenergic innervation of the common and internal carotid arteries and abdominal aorta was very sparse in the 24 month rat compared to the young adult in which these vessels were surrounded by dense fluorescent plexuses. Peripheral arteriolar innervation in the pancreas was apparently similar in both age-groups. The present study suggests that the density of adrenergic innervation varies within the constituents of the cardiovascular system in aged rats.

Effect of combined cold and pharmacological ischaemic cardioplegia on myocardial intrinsic sympatho-adrenergic system during coronary bypass surgery

The effect of combined cold and pharmacological ischaemic cardioplegia on the structural integrity and the degree of the functional activity of the inbuilt intrinsic sympatho-adrenergic nervous system was studied by means of fluorescence microscopy of atrial myocardial biopsies obtained in the course of coronary bypass surgery on 8 consecutive patients. The specimens were taken 1) before starting extracorporeal circulation (controls), and 2) at decannulation (i.e. after cold cardioplegic ischaemic asystole and subsequent coronary reperfusion). The cardioplegia was induced by perfusing the coronary arteries via the aortic root with cold "cardioplegic solution" after starting extracorporeal circulation, venting the left ventricle and cross-clamping the ascending aorta. The specimens were processed for semi-quantitative fluorescence histochemical analysis. No changes were observed. Thus, it is concluded that the procedure of the combined cold and pharmacological ischaemic cardioplegia obviously preserves well the neural noradrenalin of the heart, a vital means of compensating for decreasing myocardial contractility. As the clinical parallelism, all patients made a smooth convalescence.

Morphology of cardiac nerves in experimental infarction of rat hearts. II. Electron microscopical findings

Alterations of cardiac nerves in myocardial infarction were investigated by electron microscopy after differing intervals in 28 rats. During the first 4 h there are, in non-myelinated nerves within the myocardium, a swelling of the axoplasm with the occurrence of 'pale' axons and swelling of axonal mitochondria and neurosecretory granules. After bursting of the axolemma, these are spilled into the adjacent interstitial space. After 4 h first myelin figures are observed, and in some axons an accumulation of neurofilaments takes place. During the second to seventh day an extensive vesicular disintegration of axonal structures develops. Because of regressive changes, axons cannot be identified with certainty within the necrosis. After two or three weeks nerves with lamellar enfoldings of cytoplasmic processes corresponding to Büngner bands can be seen at the infarction border. These nerves may contain only a few residual axons. Myelinated nerves show a mainly vesicular disintegration. The results are discussed with regard to their functional significance and the special conditions of the animal model, in which ligature of the coronary artery may not only produce ischemia, but may also, by simultaneous ligature of the adjacent cardiac nerves, induce Wallerian degeneration.

Effect of cold ischaemic arrest and subsequent coronary reperfusion on the intrinsic adrenergic innervation and neural noradrenaline of the atrial myocardium during aortic valve replacement

The effect of cold ischaemic arrest (aortic cross-clamping for 50-70 min during general hypothermia of +30 degrees C, associated with local cardiac cooling with +4 degrees C saline solution) and subsequent coronary reperfusion (20-30 min) on the intrinsic adrenergic innervation of the right atrial myocardium, was studied in 10 patients in the course of prosthetic aortic valve replacement using the glyoxylic acid-induced fluorescence histochemical method. No clear changes were observed: (a) the morphological integrity of the intrinsic adrenergic nerve net remained intact, (b) no obvious depletion occurred in the neural noradrenaline level, (c) the procedure did not affect the "droplet fibres" (i.e. huge axonal accumulations of noradrenaline). Thus, the common need for catecholamine support during and after weaning off from cardiopulmonary bypass does not seem to be explained by damage to the adrenergic axons or depletion of the adrenergic neurotransmitter noradrenaline.

Adrenergic innervation of the human gall bladder

Adrenergic innervation of the human gall bladder was studied using two specific fluorescence histochemical methods. Blue-green fluorescing varicose nerves were scarce and mostly followed the course of blood vessels as typical perivascular plexuses. However, some adrenergic nerves not associated with the vessels were occasionally seen, as well as structures suggestive of a pericellular arrangement of varicose adrenergic nerve terminals on non-fluorescing ganglion cells. A few enterochromaffin cells were seen in the epithelial lining, also in the deep invaginations obviously representing the Aschoff-Rokitansky sinuses. Occasionally, small rounded cells with a rounded, relatively large nucleus, and exhibiting a weak yellow-green to blue-green granular cytoplasmic fluorescence, were observed in the wall of the gall bladder. The possible functional and evolutionary significance of these neural and endocrine elements was discussed against the data on physiological and pharmacological studies obtained from the literature. It was concluded that their significance is, in all probability, secondary to the influence of the intestinal polypeptide hormones, vagal innervation and circulating catecholamines upon the normal function of the gall bladder. The glyoxylic acid-induced fluorescence histochemical method was found to be superior to the conventional formaldehyde technique in studies on human tissue.

Rectal mucosal adrenergic innervation and enterochromaffin cells in ulcerative colitis and irritable colon

Rectal mucosal biopsies of 13 patients suffering from ulcerative colitis, 7 patients presenting symptomatology typical of irritable colon, and 7 control persons were studied by the recently introduced glyoxylic-acid-induced fluorescence histochemical method. In ulcerative colitis, compared to control specimens: 1) the density of the adrenergic nerve network was significantly pronounced; 2) the mean diameter of the varicosities and the proportional share of large varicosities were increased, as well as the number of varicosities per a given length of an axon; 3) the intensity of the fluorescence of varicosities of comparable size was significantly increased; 4) the number of enterochromaffin cells was significantly decreased. In irritable colon, compared to control specimens, the number of enterochromaffin cells was significantly increased. These findings suggest that biogenic amines are somehow involved in both ulcerative colitis and irritable colon. The fluorescence histochemical method used was found sensitive, specific, and suitable for comparative studies on human clinical material.