Publications by authors named "Socci R"

Several studies have demonstrated that plasma renin-angiotensin activity is reduced in rats administered a high salt diet. We evaluated changes in plasma and tissue levels of aldosterone (ALDO) and angiotensin II (A-II), as well as the reduced-to-oxidized glutathione ratio. Male Dahl salt-sensitive (SS) rats were placed on either a high-salt (8% NaCl; HS) or a normal-salt (0.

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The purpose of this study was to determine the potential role of brain natriuretic peptide (BNP) in the PD128,907 (a dopamine D2/D3 receptor agonist)-induced ocular hypotension in rabbits. The effects of topical application of PD128,907 (75, 250, 750 microg) on intraocular pressure (IOP) were investigated. The lowest dose (75 microg) did not alter IOP; while the higher doses (250 and 750 microg) reduced IOP bilaterally.

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The purpose of this study was to investigate mechanisms of suppression of norepinephrine release by 7-OH-DPAT, a dopamine D(2)/D(3) receptor agonist, in PC12 cells pretreated with nerve growth factor (NGF). 7-OH-DPAT caused inhibition of basal and K(+)-evoked norepinephrine release, which could be blocked by pretreatment with raclopride, a D(2)/D(3) receptor antagonist. Moreover, dopamine D(2) and D(3 )receptors were identified by immunocytochemistry.

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Background: Impairment of endothelial function during hypertension is associated with increased production of superoxide radicals and reduced antioxidants. We investigated the involvement of oxidative stress in Dahl salt-sensitive (SS) and salt-resistant (SR) rats.

Methods: For a 2-week period, male rats were fed either high salt (HS; 8% sodium chloride) or low salt (LS; 0.

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The purpose of this study is to determine the mechanisms of action involved in the ocular hypertension induced by 4-aminopyridine (4-AP), a voltage-dependent potassium (K+) channel blocker, in rabbits. Topical application of 4-AP elevated intraocular pressure (IOP). This action caused increases in the aqueous flow rate as well as aqueous levels of protein and norepinephrine.

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Background: Hypertension induced by oxidative stress has been demonstrated in normal rats. In the current study, we investigated the effect of the oral AT(1) receptor blocker losartan (10 mmol/kg/day) on oxidative stress, induced by glutathione (GSH) depletion (using buthionine-sulfoximine, BSO, 30 mmol/L/day in the drinking water), in Sprague-Dawley rats.

Methods: Mean arterial pressure (MAP) was measured by tail-cuff plethysmography and the plasma levels of total 8-isoprostane, nitric oxide, prostacyclin, thromboxane A(2), angiotensin II, aldosterone, and aortic cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) were determined by enzyme immunoassay.

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The reduction in mean arterial pressure observed in astronauts may be related to the impairment of autonomic function and/or excessive production of endothelium-derived relaxing factors. Here, we examined the role of a nitric oxide synthase II (NOS II) inhibitor AMT (2-amino-dihydro-6-methyl-4H-1,3-thiazine) against the post-suspension reduction in mean arterial pressure (MAP) in conscious male Sprague-Dawley rats. Direct MAP and heart rate were determined prior to tail-suspension, daily during the 7-day suspension and every 2 hrs post-suspension.

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Impairment in cardiovascular functions sometimes manifested in astronauts during standing postflight, may be related to the diminished autonomic function and/or excessive production of endothelium-dependent relaxing factors. In the present study, using the 30 degrees head-down tilt (HDT) model, we compared the cardiovascular and biochemical effects of 7 days of suspension and a subsequent 6-h post-suspension period between suspended and non-suspended conscious female Sprague-Dawley rats. Mean arterial pressure (MAP) and heart rate were measured prior to suspension (basal), daily thereafter, and every 2h post-suspension.

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The cardiovascular and biochemical responses during acute oxidative stress induced by D,L-buthionine-(S,R)-sulfoximine (BSO) were investigated in Sprague-Dawley rats. Mean arterial pressure, heart rate and vascular reactivity were measured after subcutaneous injection of BSO (4 mmol/kg). Control rats received saline.

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Orthostatic hypotension is a serious condition that is sometimes manifested in astronauts during standing postflight. These observations may be related to impairment of autonomic function and/or excessive production of endothelium-dependent relaxing factors. To evaluate the role of the cyclooxygenase inhibitor indomethacin as a countermeasure against the post-suspension reduction in mean arterial pressure (MAP), we examined the cardiovascular responses to 7-day 30 degrees tail-suspension and a subsequent 6-hr post-suspension period in conscious male Sprague-Dawley rats.

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Background: Oxidative stress, associated with increased plasma isoprostane (ISO) and reductions in plasma glutathione (GSH), has been shown to cause severe hypertension in normal rats. Palm oil (PO), with an unsaturated-to-saturated fatty acid ratio close to one and rich in antioxidant vitamins, has been investigated for its beneficial effects on arterial thrombosis and atherosclerosis. In this study, the effect of PO on oxidative stress induced by inhibition of GSH synthesis (using buthionine sulfoximine [BSO]) was examined.

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Cardiovascular deconditioning, sometimes manifested in astronauts during standing postflight, may be related to the impairment of autonomic function and/or excessive production of endothelium-dependent relaxing factors. In the present study, we examined the cardiovascular responses to 7-day 30 degrees tail-suspension and a subsequent 6-h post-suspension period in conscious male Sprague-Dawley rats to determine the role of prostacyclin in the observed post-suspension reduction in mean arterial pressure (MAP). The specific prostacyclin synthase inhibitor U-51605 (0.

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Cardiovascular adaptations observed during exposure to microgravity results in impairment of baroreflex activity partially as a result of fluid and electrolyte shifts. The head-down tilt rat model mimics some of the physiological observations that have been made in astronauts. We examined the effects of salt-loading on baroreflex activity after 7 day simulated microgravity (30 degrees tail-suspension) and the subsequent 6 hr post-suspension in Sprague-Dawley (SD) rats, using low salt (0.

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A simple and widely used homocysteine HPLC procedure was applied for the HPLC identification and quantitation of glutathione in plasma. The method, which utilizes SBDF as a derivatizing agent utilizes only 50 microl of sample volume. Linear quantitative response curve was generated for glutathione over a concentration range of 0.

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Chronic infusion of angiotensin-(1-7) [Ang-(1-7)] lowers blood pressure in salt-induced and spontaneously hypertensive (SHR) rats. In the present study, we have examined the acute effect of Ang-(1-7) in salt-induced hypertension using Dahl salt-sensitive rats placed on low (0.3%) or high (8.

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A large number of astronauts returning from spaceflight experience orthostatic hypotension. This hypotension may be due to overproduction of vasodilatory mediators, such as nitric oxide (NO) and prostaglandins. To evaluate the role of the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) as a countermeasure against the post-suspension reduction in mean arterial pressure (MAP), we assessed the cardiovascular responses and vascular reactivity to 7-day 30 degrees tail-suspension and a subsequent 6 hr post-suspension period in conscious rats.

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Prolonged exposure to microgravity, in humans, induces cardiovascular deconditioning and impairment of baroreflex activity partially as a result of fluid and electrolyte shifts. Animal models of simulated microgravity have been developed to mimic the above responses. We examined the effects of both 24 hr whole body suspension and 7 day tail-suspension and the subsequent 6 hr post-suspension in salt-loaded (2 wks on 8% NaCl diet) Dahl salt-sensitive rats.

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Cardiovascular deconditioning manifested by reduction in mean arterial pressure (MAP) and cardioaccleration are usually observed in astronauts during standing postflight. The head-down tilt (HDT) rat model with "unloaded" hindlimbs has been extensively studied because some of the observed responses mimic observations made during exposure to microgravity. Angiotensin-(1-7) is a biologically active component of the renin-angiotensin system that acts to oppose the pressor and proliferative actions of Angiotensin II.

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Chronic infusion of angiotensin (1-7) [Ang-(1-7)] lowers blood pressure in spontaneously hypertensive rats (SHR). To assess the role of Ang-(1-7) in salt-induced hypertension, Ang-(1-7) (24 microg/kg/hr) or saline was administered chronically via osmotic minipump into the jugular vein of 5-6 wk-old male (M) and female (F) Dahl salt-sensitive rats placed on a high-salt (8% NaCl) diet for 2 weeks. Blood pressure (BP) and heart rate were measured prior to the start of the diet and weekly thereafter.

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To evaluate gender differences in salt-induced hypertension, female and male Dahl salt-sensitive rats were fed high (8.0% NaCl, HS) and low (0.3% NaCl, LS) salt diets.

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Microgravity is known to induce orthostatic intolerance and baroreflex impairment in astronauts. Cardiovascular responses observed in 30 degrees head-down tilt rat models, whether 24 hr whole body suspension (WBS) or 7 day tail-suspension (TS), mimic observations made during exposure to microgravity. We evaluated the cardiovascular effects of simulated microgravity and the subsequent post-suspension in rats using the above models.

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To understand the role of nitric oxide in salt-induced hypertension, we evaluated cardiovascular, hemodynamic and biochemical parameters in Dahl salt-sensitive rats fed low (0.3%) and high (8.0%) sodium diets.

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Genetic factors, diet, and salt sensitivity have all been implicated in hypertension. To further understand the mechanisms involved in salt-induced hypertension, cardiovascular, hemodynamics, and biochemical parameters in Dahl salt-sensitive rats were evaluated in animals on high- and low-sodium diets. During a 4-week treatment period, blood pressure was significantly elevated in the high (8.

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