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Biomedical subjects

A Renzi

Publications and source records attributed to A Renzi.

At least 91 records · Page 5Linked to original sources
PubMed1990

The anteroventral third ventricle (AV3V) region is essential for pressor, dipsogenic and natriuretic responses to central carbachol.

In the present study we investigated the effect of anteroventral third ventricle (AV3V) lesion on pressor, dipsogenic and natriuretic responses produced by the intracerebroventricular (i.c.v.) injection of a cholinergic agonist (carbachol). Freely moving rats with AV3V or sham lesion (1-2 days and 9-12 days) and a delay cannula implanted into the lateral ventricle were studied. Changes in mean arterial pressure (MAP, 1 h record), water intake (1 h) and Na+ excretion (2 h) were analysed after i.c.v. injection of carbachol (7.5 nmol). In sham rats, i.c.v. injection of carbachol produced an increase in MAP (35 +/- 2 mmHg), water ingestion (7.7 +/- 1.2 ml/h) and Na+ excretion (626 +/- 42 microEq/120 min). The effects of i.c.v. carbachol injection were reduced 1-2 days after AV3V lesion (delta MAP = 6 +/- 2 mmHg, water ingestion = 0.3 +/- 0.3 ml/h and Na+ excretion = 31 +/- 11 microEq/120 min) and 9-12 days (delta MAP = 11 +/- 3 mmHg, water ingestion = 3.3 +/- 0.9 ml/h and Na+ excretion = 37 +/- 11 microEq/120 min). These results show that the AV3V region is essential for the full development of the pressor, dipsogenic and natriuretic responses produced by central cholinergic receptors.

Animals↗
PubMed1990

Role of central alpha 1- and alpha 2-adrenoceptors on the dipsogenic and cardiovascular effect of angiotensin II.

We investigated the effects of previous central treatment with prazosin (an alpha 1-adrenoceptor antagonist) or clonidine (an alpha 2-adrenoceptor agonist) on the dipsogenic, pressor and tachycardic responses produced by intracerebroventricular (ICV) injection of angiotensin II (AII) in conscious rats. Holtzman rats with a chronic cannula implanted in the lateral ventricle were tested for dipsogenic and cardiovascular (arterial pressure and heart rate) responses in separate experiments. Previous ICV treatment with clonidine (20, 40, 80 and 120 nmol) abolished the pressor, tachycardic and dipsogenic effects of ICV AII. After all doses of prazosin (40, 80 and 120 nmol), AII induced bradycardic responses, but only the 80 and 120 nmol doses of prazosin reduced the pressor responses to AII. Prazosin produced no alteration in the dipsogenic effect of AII. The results show that the periventricular alpha 1-adrenoceptors are involved only in the cardiovascular responses produced by central AII, whereas clonidine acting through alpha 2-adrenergic and/or imidazole receptors can modulate all actions of AII.

Angiotensin II↗
PubMed1990

Interaction between cholinergic and adrenergic pathways of the hypothalamic ventromedial nucleus on cardiovascular regulation.

In this work we studied the possible interaction between cholinergic (muscarinic and nicotinic) and adrenergic (alpha 1- and beta-adrenergic) pathways of the hypothalamic ventromedial nucleus on the regulation of arterial pressure and heart rate in conscious normotensive rats. Mean arterial pressure and heart rate were recorded in rats with cerebral chronic stainless steel cannulae implanted directly into the ventromedial nucleus. The changes in arterial pressure and heart rate produced by the injection of the cholinergic agonist (carbachol or nicotine) into the ventromedial nucleus were studied before and after the injection of prazosin (an alpha 1-adrenergic antagonist) or propranolol (a beta-adrenergic antagonist) into this same area. The injection of carbachol (2 nmol) or nicotine (40 mmol) into the ventromedial nucleus induced pressor and tachycardia responses. Previous treatment with prazosin or propranolol blocked the pressor response to carbachol and nicotine. Propranolol also abolished the tachycardic response to carbachol or nicotine, but prazosin reduced only the tachycardia produced by carbachol into the ventromedial nucleus. These results show an interaction between cholinergic and adrenergic pathways of the ventromedial nucleus affecting cardiovascular regulation and suggest that the alpha 1- and beta-adrenoceptors of this nucleus are involved in these responses.

Animals↗
PubMed1990

Morphological, morphometric and stereological study of submandibular glands in rats with lesion of the anteroventral region of the third ventricle (AV3V).

Lesions of the antero-ventral region of the third ventricle induce in the rat submandibular gland parenchyma, atrophy through vascular ischemia, and simultaneously increased fibrosis of the connective tissue, probably by alteration of the pituitary gonadotropins (FSH, LH), thyrotrophic hormone (TSH), growth hormone and probably insulin levels.

Animals↗
PubMed1990

Interaction between cholinergic and opiate receptors of the lateral hypothalamus in the control of renal excretion in rats.

The present study was carried out to investigate the participation and interaction between cholinergic and opiate receptors of the lateral hypothalamus (LH) in the regulation of Na+, K+ and water excretion. Male Holtzman rats were implanted with chronic cerebral cannulas into the LH. Urine was collected over a period of 2 h after injection of carbachol, FK-p33824 + carbachol or naloxone + carbachol into the LH. Carbachol (8 nmol) reduced urinary volume and increased Na+ excretion. Previous injection of FK-33824 (100 ng) into the LH increased the antidiuretic effect of carbachol, but blocked the increase in Na+ excretion and decreased K+ excretion. Naloxone (10 micrograms) produced no changes in the effect of carbachol on renal excretion. These data show an inhibitory effect of opiate receptors on the changes in urinary Na+ and K+ excretion that are induced by cholinergic stimulation of the LH in rats, and a potentiating effect on antidiuresis.

Animals↗
PubMed1990

The effect of phentolamine on the pressor response to centrally administered clonidine in rats.

In the present study we investigate the effect of the previous injection of phentolamine (a nonspecific alpha-adrenergic antagonist) into the lateral hypothalamus (LH) and lateral ventricle (LV) on the pressor and bradycardic responses produced by the injection of clonidine (an alpha 2-adrenergic agonist) into these same areas of conscious rats. The injection of clonidine into the LV and LH produced pressor (39 +/- 5 and 38 +/- 3 mmHg, respectively) and bradycardic responses (-65 +/- 16 and -94 +/- 13 bpm, respectively). Previous injection of phentolamine into the LH or LV reduced the pressor response to clonidine injected into the same areas (delta MAP = 13 +/- 6 mmHg for LH and 1 +/- 3 mmHg for LV). No reduction was observed when clonidine was injected into the LV after the injection of phentolamine into the LH. No changes in bradycardic responses were observed after treatment with phentolamine. The present results show the participation of alpha-adrenergic receptors in the pressor response to centrally administered clonidine but not in the bradycardic response. The data also suggest that the pressor effect produced by the injection of clonidine into the LH is due to the activation of alpha-adrenergic receptors located specifically in this area. The pressor response after injection of clonidine into the LV and of phentolamine into the LH is due to the action of clonidine on other cerebral areas.

Animals↗
PubMed1990

Effect of dehydration on the increase of arterial pressure and renal electrolyte excretion produced by central cholinergic stimulation in rats.

Natriuresis, kaliuresis, diuresis, arterial pressure and heart rate were studied in rats following dehydration and cholinergic stimulation of the medial septal area (MSA). The increase in renal Na+ and K+ excretion produced by the injection of carbachol (2 nmol) into the MSA in normal hydrated rats was abolished in 48-h water-deprived rats. Urinary volume was also reduced. Cholinergic stimulation of the MSA produced a smaller increase in arterial pressure in 48-h water-deprived rats compared to normal hydrated animals. No change was observed in heart rate. These results show that hydration state is essential for the central cholinergic control of electrolyte excretion and increase in arterial pressure.

Animals↗
PubMed1989

Carbachol injection into the medial preoptic area induces natriuresis, kaliuresis and antidiuresis in rats.

The microinjection of carbachol into the medial preoptic area (MPO) of the rat induced natriuresis, kaliuresis and anti-diuresis in a dose-related manner. Atropine blocked all responses to carbachol. Hexamethonium impaired the dose-response effect of carbachol on kaliuresis, but had no effect on natriuresis and enhanced the antidiuretic effect of carbachol. Nicotine alone had no effects, but pre-treatment with nicotine enhanced the responses to carbachol. These data show that activity of the muscarinic receptors of the MPO increases renal electrolyte and reduces water excretion. They also suggest that nicotinic receptors have an inhibitory effect on water excretion. Nicotine could act through mechanisms unrelated to nicotinic receptors to enhance the effect of the carbachol.

Animals↗
PubMed1989

Pressor responses of clonidine injected into some prosencephalic areas of conscious rats.

The objective of this investigation was to study the effect of clonidine injection into some prosencephalic areas of unanesthetized rats on mean arterial pressure (MAP) and heart rate (HR). Injection of 40 nmol clonidine in 1.0 lambda 150 mM NaCl into the medial septal area, lateral hypothalamus, lateral preoptic area and lateral ventricle caused the same increase in MAP, 38 +/- 3 to 41 +/- 5 mmHg, and decrease in HR, -65 +/- 10 to -94 +/- 13 bpm (mean +/- SEM, N = 9 to 11 animals). These results show that clonidine can act on several prosencephalic areas to induce a pressor response in the conscious rat.

Animals↗
PubMed1988

Ecology of viruses isolated from sand flies in Italy and characterized of a new Phlebovirus (Arabia virus).

A total of 84 virus strains was obtained from 16,374 male and female sand flies (Phlebotomus perniciosus and P. perfiliewi) collected in two localities of Tuscany region in Italy between 1980 and 1985. Thirty-seven (44%) were identified as Toscana virus (family Bunyaviridae, genus Phlebovirus) and 47 (56%) as a new member of the Phlebotomus fever serogroup, Arbia virus. The characteristics of this new serotype are described. The overall virus isolation rate from sand flies was 0.5 per 100 insects processed. Virus isolation rates for both viruses were similar in different years and in the two localities, suggesting that the two virus types were active in the sand fly population simultaneously. Each year, the largest number of isolates were obtained during July, corresponding to the period of maximal sand fly population density. Both viruses were repeatedly isolated from male sand flies, suggesting transovarial transmission in nature. Serologic data showed no evidence of infection among domestic and wild animals. However, a strain of Toscana virus was isolated from the brain of a bat (Pipistrellus kuhli), indicating a possible involvement of this species in the ecology of the virus. Serologic tests did not provide definitive evidence for human infection by Arbia virus.

Animals↗
PubMed1988

Effects of intracerebroventricular infusion of angiotensin II and related peptides on water and sodium ingestion and excretion.

The objective of the present study was to investigate the effects of an angiotensin II (AII) analogue, Des-Asp1-AII and of two competitive blockers, [Leu8]-AII and [octanoyl-Leu8]-AII, infused intracerebroventricularly on the ingestion of water and of a 3% NaCl solution, as well as on diuresis and natriuresis in normal rats and in adrenalectomized and deoxycorticosterone (DOCA)-treated rats. Both AII and Des-Asp1-AII increased water and 3% NaCl intake and increased urine and Na+ excretion, the effect of AII being more intense. Except for 3% NaCl, the responses of all other parameters were totally or partially reduced by previous treatment with [Leu8]-AII or [octanoyl-Leu8]-AII. Subcutaneous DOCA injection caused water ingestion. Previous treatment with DOCA increased the response to AII for the ingestion of 3% NaCl and inhibited sodium excretion. The results obtained for adrenalectomized rats treated with DOCA, AII and analogous agonists did not differ from those observed in normal rats. These data suggest a possible synergism between the cerebral and renal renin-angiotensin systems in the regulation of the physiological parameters studied.

Adrenalectomy↗
PubMed1987

Integration between the lateral preoptic area and subfornical organ in the regulation of water intake and hemodynamics in the rat.

1. The injection of a hypertonic saline solution (0.2 M NaCl) into the lateral preoptic area of the rat produced an increase in water intake that was further increased by the injection of angiotensin II (4 ng) into the subfornical organ. An increase in arterial pressure was also observed. Increase in heart rate was noted after injection of 0.2 M NaCl into the lateral preoptic area. 2. The injection of hypertonic NaCl into the subfornical organ increased water intake and the injection of 4 ng of angiotensin II into the lateral preoptic area augmented this effect. The injection of 0.2 M NaCl into the subfornical organ did not affect blood pressure or heart rate, whereas the injection of angiotensin II into the lateral preoptic area resulted in an increase in these parameters. 3. Intravenous perfusion of angiotensin II (40 ng microliters-1 min-1) caused increased water intake, arterial pressure and heart rate. Dehydration of the lateral preoptic area by 0.2 M NaCl resulted in a summation of effects for water intake alone. 4. Intravenous perfusion with 0.5 M NaCl caused an increase in water intake which was further increased after the injection of angiotensin II (4 ng) into the subfornical organ and angiotensin II (4 ng) into the lateral preoptic area. Arterial pressure and heart rate also increased, remaining unchanged when angiotensin II was injected into the subfornical organ or into the lateral preoptic area. 5. These results suggest interactions between the two areas in the regulation of cardiovascular and thirst mechanisms. However, cardiovascular regulation and the regulation of body fluids may be stimulated by physiological responses to separate mechanisms.

Angiotensin II↗
PubMedDate not supplied

[Pharmacological sympathetic block in complex regional pain syndrome].

PURPOSE: The Complex Regional Pain Syndrome (CRPS) is a chronic pain state provoked by lesions of the soft tissues or of the bony tissues (type CRPS-I or reflex sympathetic dystrophy-RSD) or by lesions of the nerves (type CRPS-II or causalgia) with vegetative alterations (perspiration, vasomotory alterations) and trophic alterations (bony cutaneous atrophy, alopecia, articular contractures). The pharmacological block of the sympathetic nerves through a peripheral vein is inserted in the multidisciplinary approach that characterizes the therapy of this syndrome. MATERIALS AND METHODS: A retrospective survey was carried out on a group of 185 patients affected by RDS/CRPS with block of the sympathetic nerves through a peripheral vein with guanethidine. Superior limb: Inflation of the tourniquet till disappearance of the radial wrist. Cannulation of a peripheral vein with Butterfly needle n. 23. Guanethidine 10 mg, lidocaine 20 mg, sodic heparin 500 u.i, NaCl 0.9% 20 ml. Injection in 5 minutes. Permanence of the pneumatic tourniquet inflated above systolic blood pressure for 15 minutes. Deflation slowly. Inferior limb: Inflation of the tourniquet till disappearance of the pedidium wrist. Cannulation of a peripheral vein with Butterfly needle n. 23. Guanethidine 20 mg, lidocaine 40 mg, sodic heparin 1000 u.i, NaCl 0.9% 40 ml. Injection in 5 minutes. Permanence of the pneumatic tourniquet inflated above systolic blood pressure for 15 minutes. Deflation slowly. RESULTS: The first stage (hyperemic) showed the highest incidence of remissions: (83, 33%). Even in the second stage (dystrophic) the answer to the therapy has been fundamentally positive: (53, 68%). In the third stage (atrophic) the results have been more modest: (8, 33%). CONCLUSIONS: The block of sympathetic system with guanethidine is still an important method in the therapy of the CRPS; in fact it is surely less invading than the blocks of the stellate ganglion or of the lumbar sympathetic.

Adolescent↗