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Biomedical subjects

W Debinski

Publications and source records attributed to W Debinski.

At least 55 records · Page 3Linked to original sources
PubMed1990

Atrial natriuretic factor is a new neuromodulatory peptide.

In this commentary, we will briefly discuss the potential regulatory role of atrial natriuretic factor in peripheral autonomic nervous system function. The focus will be on atrial natriuretic factor's involvement in cardiovascular homeostasis through its peripheral effect on sympathetic nervous activity, which may complement its humoral role. [Kuchel et al. (1987) Life Sci. 40, 1545-1551; Lang et al. (1985) Nature 314, 264-266]. We will attempt to support the hypothesis of its neuromodulatory action on efferent autonomic outflow. Specifically, the role of atrial natriuretic factor in the regulation of the synthesis and release of neurotransmitters and in synaptic transmission at the level of the sympathetic ganglia will be outlined. Its potential usefulness in neurobiological studies will also be indicated.

Animals↗
PubMed1990

Atrial natriuretic factor constitutes an intrinsic functional unit within superior cervical ganglia of the rat.

The molecular forms of atrial natriuretic factor were studied in the sympathetic ganglia of the rat. The peptide atrial natriuretic factor was also tested for its ability to induce intracellular changes in ganglionic elements. Chromatographic evaluation of extracted ganglionic atrial natriuretic factor revealed the presence of proatrial natriuretic factor together with lower molecular weight peptides. Atrial natriuretic factor induced a maximal six-fold increase of cGMP accumulation within ganglia in vitro, most probably in principal ganglionic cells. Its effect on cGMP was not mediated by acetylcholine or any other neurotransmitter because it persisted after muscarinic receptor blockade and in a calcium-free medium and was not affected by ganglia decentralization. Thus, atrial natriuretic factor appears to be produced by a structural neural component of ganglia (in preganglionic cholinergic neurons or small intensely fluorescent cells?) and has receptors at sites different from its source. It is suggested that atrial natriuretic factor may be locally involved in the process of neurotransmission and may be yet another peptide neurotransmitter and/or neuromodulator.

Animals↗
PubMed1990

Vesicular and ganglionic norepinephrine in the rat: progressive increase with age.

This study analyzed dopamine (DA) and norepinephrine (NE) in the synaptic vesicles and cytoplasm of brains of rats of 2 months and 14 months. The data revealed a clear NE increase in the synaptic vesicles of the 14-month-old rats, contrasting with NE in the cytoplasmic fraction of the rat brain, which remained unchanged with age. Synaptic vesicles from different regions of rat brain, including those from the striatum, consistently exhibited higher NE than DA concentrations, suggesting that they are predominantly noradrenergic. In the brain, DA concentrations in vesicular and cytoplasmic fractions did not vary with age, whereas in the superior cervical ganglia DA and NE concentrations increased in the older rats. L-3,4-Dihydroxyphenylalanine administration significantly increased DA without affecting NE in the ganglia of rats of all ages. In the brain, such a treatment significantly raised DA only in the synaptic vesicles of the older rats, suggesting an increased facilitation of DA transport into the synaptic vesicles with age, which may account for the higher vesicular NE in the older rats.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1990

Dissociation between right atrial pressure and plasma atrial natriuretic factor following prolonged high salt intake.

The influence of prolonged high salt intake on intravascular volume, right atrial pressure, plasma atrial natriuretic factor, and extra-atrial tissue (lung, kidney, and liver) COOH- and NH2-terminal atrial natriuretic factor content was investigated in normotensive rats. Despite prolonged high salt (8% NaCl) intake for 5 weeks, total intravascular volume was not impaired. However, right atrial pressure was increased by 54% (p less than 0.01) after salt loading. Although this increment in right atrial pressure should favor atrial natriuretic factor release after NaCl intake, plasma atrial natriuretic factor (COOH-terminal) concentrations markedly decreased from 97.8 +/- 27 to 38.9 +/- 8 pg/mL. Sodium and circulatory homeostasis was, however, well preserved. The lungs contained the highest levels of COOH- and NH2-terminal atrial natriuretic factor. Salt loading resulted in increased concentrations of low as well as high molecular weight atrial natriuretic factor in the lung but not in the kidney or the liver. Our study indicates a limited role of atrial natriuretic factor in adaptation to prolonged salt consumption in rats. Dissociation between right atrial pressure and plasma atrial natriuretic factor after salt intake implicates other factors regulating circulating peptide levels. Prolonged salt intake increases lung generation of atrial natriuretic factor.

Animals↗
PubMed1990

ANF disappearance and tissue distribution in rats.

The disappearance of [125I]atrial natriuretic factor (ANF; Ser99-Tyr126) from the circulation and its tissue distribution with or without nonlabeled ANF pretreatment were investigated in normotensive Sprague-Dawley rats. Preadministration of the cold peptide increased plasma radioactivity levels for over 8 min following labeled ANF injection but did not change the half-life of circulating labeled ANF. The metabolic clearance rate (MCR) and volume of distribution in the first, second, and steady state phase were significantly decreased after cold ANF pretreatment. Circulating iodo-labeled ANF was taken up by several organs, even by tissues such as fat or bone, but its urinary excretion was very low. The highest uptake was found in the liver (16 +/- 1% of the injected dose), lung (14 +/- 1%), and kidney (12 +/- 1%), diminishing by 21, 89, and 59%, respectively, after cold ANF preinjection. The brain radioactivity was negligible implying an inability of [125I]ANF to cross the blood-brain barrier. Our data underscore the importance of the uptake-mediated, cold ANF preadministration suppressible clearance of ANF from the circulation, probably one of its basic elimination mechanisms. The liver, lung, and kidney are probably the most important participants in the MCR of ANF.

Animals↗
PubMed1990

Effect of prolonged high salt diet on atrial natriuretic factor in rats.

Normotensive Sprague-Dawley rats were given 8% NaCl for 5 weeks. This salt load did not affect their blood pressure nor hematocrit, and plasma atrial natriuretic factor (ANF) showed no change at 3 weeks but decreased after 5 weeks of the experimental period when compared with control rats. The responsiveness of particulate guanylate cyclase and formation of cGMP in ANF target organs suggested an augmented baseline activity of the cGMP system but its relative hyporesponsiveness to exogenous ANF following prolonged salt loading. Decreased plasma ANF levels cannot be explained by its altered production since atrial levels of the peptide were comparable in rats with or without salt loading. Atrial ANF mRNA was unaffected by the salt regimen. This study demonstrates that plasma ANF does not increase during long-term NaCl loading and even decreases after 5 weeks of 8% NaCl. The changes in plasma ANF are associated with changes in the functional state of ANF receptors coupled to particulate guanylate cyclase, but in the opposite direction than expected from lowered plasma ANF. Thus, ANF may not play a significant role in the regulation of sodium excretion in response to prolonged high salt consumption or, if it does, it is not reflected by expected changes in its plasma levels.

Adrenal Cortex↗
PubMed1989

A defective beta-hydroxylation of dopamine may precede the full development of hypertension in spontaneously hypertensive rats.

A possible mechanism of the previously observed increased adrenal dopamine release and tissue content in spontaneously hypertensive rats (SHR) was explored. The following changes in dopamine beta-hydroxylase activity and catecholamines were noted. At age four weeks (normotensive) or 12 weeks (hypertensive), SHR had lower dopamine beta-hydroxylase activity in the adrenals, heart ventricle and spleen than Wistar Kyoto rats. Tissue dopamine beta-hydroxylase activity in Wistar Kyoto rats was increased with age in the atria but decreased in the ventricles and did not change in the spleen. SHR also had reduced right heart atrial dopamine beta-hydroxylase activity in the hypertensive stage and an overall increase in atrial dopamine content even in the prehypertensive state compared to Wistar Kyoto rats. The increase in noradrenaline content seen with age in the right atrium and spleen in Wistar Kyoto rats was not found in SHR, possibly because of concomitantly decreased dopamine beta-hydroxylase activity. An augmented dopamine:noradrenaline ratio in the spleen of hypertensive SHR may also have been related to an abnormality of the synthesis of noradrenaline from dopamine not necessarily reflected by tissue dopamine beta-hydroxylase determination. A defect of beta-hydroxylation, partly attributable to deficient dopamine beta-hydroxylase activity, may thus precede hypertension and contribute to the hyperdopaminergic state found in SHR.

Adrenal Glands↗
PubMed1988

Atrial natriuretic factor in sympathetic ganglia of the rat: dependence on cholinergic innervation.

Atrial natriuretic factor is detectable in the peripheral autonomic ganglia of the rat by radioimmunoassay and immunohistochemistry. In the present study, surgical and neurochemical methods were used to evaluate the source of this peptide in sympathetic ganglia. Decentralization of the ganglia and/or central administration of colchicine diminished the atrial natriuretic factor content in para- and prevertebral ganglia. Axotomy did not affect levels of ganglionic atrial natriuretic factor. A messenger ribonucleic acid species hybridizing with rat atrial natriuretic factor complementary deoxyribonucleic acid was not found within the total ribonucleic acid extracted from superior cervical ganglia. These results indicate a direct dependence of ganglionic atrial natriuretic factor on cholinergic innervation.

Acetylcholine↗
PubMed1988

Ganglionic immunoreactive atrial natriuretic factor in rat experimental hypertension.

Because previous data have suggested a dependence of ganglionic atrial natriuretic factor (ANF) content on preganglionic cholinergic input, we investigated the possibility that the increased neural activity observed in spontaneously hypertensive rats (SHR) may be reflected by ganglionic immunoreactive ANF levels. Four-week-old normotensive SHR had celiac ganglionic immunoreactive ANF values comparable to those of Wistar-Kyoto rats (WKY). When they became hypertensive, however, at 12 weeks of age, the SHR manifested higher immunoreactive ANF levels in celiac ganglia than the WKY group (25.3 +/- 2.6 vs 14.5 +/- 1.7 pg/ganglion; p less than 0.01), but there were no differences in levels in the superior cervical and nodose ganglia. The values in celiac ganglia were quadrupled on the average in hypertensive Dahl salt-sensitive rats under the influence of an 8% salt intake for 5 weeks, but no difference was noted in any of these ganglia between this group and their salt-resistant partners. The celiac and superior cervical ganglionic immunoreactive ANF content in normotensive Sprague-Dawley rats was higher with high salt than with normal salt intake. Hypertensive rats treated with deoxycorticosterone acetate (DOCA)-salt and sham-treated controls showed immunoreactive ANF concentrations in celiac ganglia similar to those detected in Dahl rats but, again, no differences were found between groups. Thus, hypertensive SHR, compared to WKY, have higher celiac ganglionic immunoreactive ANF levels, unlike Dahl salt-sensitive and DOCA-salt animals relative to their respective controls. This increase is unique to SHR (although all three models have elevated plasma immunoreactive ANF when they are hypertensive) and to the celiac ganglia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Ganglionic, spinal cord and hypothalamic atrial natriuretic factor: its distribution, origin and possible role in spontaneously hypertensive rats.

We report the occurrence of the atrial natriuretic factor (ANF) prohormone in the hypothalamus, spinal cord and sympathetic ganglia determined by measurement of immunoreactive ANF by two peptide-specific radio-immunoassays with antibodies against near-C-terminal and near-N-terminal portions of ANF prohormone. This suggests local ANF generation in neural structures. In spontaneously hypertensive rats (SHR) we found an elevated ANF-C content in all tissues along the pathway of increased efferent sympathetic outflow, which is present in this animal model. The ANF-N was augmented in SHR only in the hypothalamus. This indicates an overall increase of neural ANF in SHR. The reported neuroinhibitory function of increased neural ANF, however, was attenuated by a decrease in the number of some brain and peripheral ganglionic ANF binding sites in SHR. It remains to be determined whether the increased neural ANF in SHR is a primary phenomenon or a compensatory increase induced by high blood pressure.

Animals↗
PubMed1987

Catecholamine, dopamine-beta-hydroxylase and atrial natriuretic factor content in separate heart chambers of cardiomyopathic hamsters.

Since previous investigations have suggested a relationship between atrial natriuretic factor (ANF) and dopamine-beta-hydroxylation, cardiomyopathic hamsters were studied for atrial and ventricular catecholamine (CA) and dopamine-beta-hydroxylase (D beta H) content as correlates to a parallel finding of markedly decreased atrial but increased ventricular ANF concentrations in these animals. It was noted that, with progressive cardiomyopathy, the reduced tissue norepinephrine (NE) content paralleled the declining D beta H activity in the atria. In the ventricles, however, the progressively-decreasing NE content was associated with an increase of D beta H. These data indicate that the NE depletion is mediated by different mechanisms in the ventricles and atria. They do not support a simple relationship between NE depletion and tissue D beta H activity or between the latter and tissue ANF concentrations.

Animals↗
PubMed1987

Atrial natriuretic factor partially inhibits the stimulated catecholamine synthesis in superior cervical ganglia of the rat.

We examined whether the atrial natriuretic factor (ANF) may affect the function of the peripheral autonomic neurons. ANF was found to inhibit the carbachol-stimulated synthesis of catecholamines from their labelled [3H]tyrosine precursor in an organ suspension of the rat superior cervical ganglia in vitro. This is compatible with the possibility that the previously observed inhibitory action of ANF on sympathetic nervous activity and the presence of immunoreactive ANF in the rat peripheral autonomic ganglia is related to an inhibitory-neuromodulatory role of ANF in the process of ganglionic neurotransmission.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

An emerging relationship between peripheral sympathetic nervous activity and atrial natriuretic factor.

The sympathetic nervous system and atrial natriuretic factor (ANF) are intimately involved in sodium, volume and blood pressure homeostasis, particularly in response to volume and pressure overloads. Although rapid progress in this field indicates several levels of interaction between both systems, the role of sympathetic nervous activity (SNA) in ANF release remains a controversial topic. There is growing evidence that ANF is an inhibitory modulator of sympathetic outflow (which in turn, may contribute to ANF's effect) and, vice-versa, SNA attenuates the target actions of ANF. Compensatory sympathetic reactions to changes induced by ANF may also have an overriding influence on its target actions. Dopamine appears to play a special role in these interactions. It is not only a precursor of norepinephrine but probably fulfills an independent function in the regulation of salt balance, similar in many respects to that of ANF.

Animals↗
PubMed1987

Catecholamines and atrial natriuretic factor in Dahl and spontaneously hypertensive rats.

We have previously demonstrated two different catecholaminergic patterns in genetic and experimental hypertension: a hyperdopaminergic state in spontaneously hypertensive (Okamoto) rats (SHR) and a hypernoradrenergic state in salt-sensitive Dahl rats. Plasma immunoreactive atrial natriuretic factor (IR ANF) concentrations increase in both models as a response to hypertension. To distinguish between the genetic and acquired components of these abnormalities, we measured adrenal dopamine-beta-hydroxylase (D beta H) activity and coeliac ganglionic atrial natriuretic factor (ANF) like immunoreactivity in the two animal strains. While adrenal D beta H activity was increased in Dahl S rats, it was diminished in SHR in the prehypertensive as well as in the hypertensive stages. In the hypertensive stage, the ANF-like immunoreactivity in the coeliac ganglia was lower in the Dahl S group but higher in SHR than in their respective normotensive controls; there were no changes in these animals when they were prehypertensive. Differences in D beta H activity, which determines the fine tuning of sympathoadrenomedullary catecholamine synthesis may account for the inheritance of mechanisms resulting in salt-sensitive hypertension (as in SHR) or salt-dependent hypertension (as in Dahl salt-sensitive rats). In contrast, plasma IR ANF concentrations may reflect a defense mechanism against hypertension. However ANF-like immunoreactivity in coeliac ganglia does not follow its plasma concentrations and changes in different directions in the two hypertensive strains; it may reflect a neuromodulatory function of ANF in the ganglionic neurotransmission and different implications of this role of ANF in the two hypertensive models.

Animals↗
PubMed1987

Presence of an atrial natriuretic factor-like peptide in the rat superior cervical ganglia.

The presence of a peptide resembling atrial natriuretic factor (ANF) was demonstrated in the peripheral sympathetic ganglia of the rat by a sensitive radioimmunoassay. Partially purified ANF-like compounds from the superior cervical ganglia exhibited biological activities which were similar to the synthetic peptide of cardiac origin; they inhibited ACTH-stimulated aldosterone release in vitro and displaced labelled [125I]-ANF from rat adrenocortical cell receptors. The exact source and role of ANF in peripheral nervous structures is not fully understood. We suggest that in sympathetic ganglia ANF may act as a neurotransmitter and/or neuromodulator in a manner similar to other neuropeptides.

Adrenal Cortex↗
PubMed1987

Contrasting dopaminergic patterns in two forms of genetic hypertension.

Dopaminergic mechanisms in genetic hypertension were explored via the measurement of catecholamine (CA) turnover, tissue concentration and urinary excretion of dopamine (DA) and its metabolites. In salt-sensitive (S) Dahl rats, the tissue concentration and urinary excretion of DA and its metabolites were decreased in response to salt loading, while adrenal dopamine-beta-hydroxylase (D beta H) activity and aldosterone responsiveness to angiotensin II (A II) were increased. In contrast, spontaneously-hypertensive rats (SHR) showed elevated tissue levels and urinary excretion of DA and its metabolites, adrenal DA turnover and ganglionic DA generation following cholinergic stimulation, but D beta H activity and aldosterone responsiveness to A II were diminished. These two patterns, the hypodopaminergic state in Dahl S rats and the hyperdopaminergic state in SHR, account for two distinct mechanisms of hypertension and precede its development. We detected striking dopaminergic activity-related similarities between Dahl S rats and low-renin essential hypertension (EH) on the one hand, and SHR and non-modulator EH patients on the other.

3,4-Dihydroxyphenylacetic Acid↗