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1.
Taking into consideration renal hypertension-induced homeostatic disorders and the key role of calcitonin gene-related peptide (CGRP) in many, systemic functions regulating systems, a question arises as to what an extent arterial hypertension affects the morphology and dynamics of pulmonary CGRP-immunopositive cell changes. The aim of the present study was to examine the distribution, morphology and dynamics of changes of CGRP-containing cells in the lungs of rats in the two-kidney, one-clip (2K1C) renovascular hypertension model. The studies were carried out on the lungs of rats after 3, 14, 28, 42, and 91 days long period from the renal artery clipping procedure. In order to identify neuroendocrine cells, immunohistochemical reaction was performed with the use of a specific antibody against CGRP. It was revealed that renovascular hypertension caused changes in the neuroendocrine, CGRP-containing cells in the lungs of rats. The changes, observed in the neuroendocrine cells, depended on time periods from experimentally induced hypertension. The highest intensity of changes in the neuroendocrine cells was observed in the lungs of rats after 14 days from the surgery.Key words: CGRP-positive cells, lung, hypertension (two-kidney one-clip), rat.  相似文献   

2.
We have demonstrated that myocardial ATP-sensitive potassium (K(ATP)) channels are implicated in the development of cardiac hypertrophy in hyperlipidemic rabbits. We investigated the effect of pravastatin on development of ventricular hypertrophy in male normolipidemic Wistar rats with two-kidney, one-clip (2K1C) hypertension and whether the attenuated hypertrophic effect was via activation of K(ATP) channels. Twenty-four hours after the left renal artery was clipped, rats were treated with one of the following therapies for 8 wk: vehicle, nicorandil (an agonist of K(ATP) channels), pravastatin, glibenclamide (an antagonist of K(ATP) channels), hydralazine, nicorandil plus glibenclamide, or pravastatin plus glibenclamide. Systolic blood pressure, relative left ventricular (LV) weight, and cardiomyocyte sizes significantly increased in vehicle-treated 2K1C rats compared with those in sham-operated rats. Treatment with either nicorandil or pravastatin significantly attenuated LV hypertrophy/body weight compared with the vehicle, which was further confirmed by downregulation of LV atrial natriuretic peptide mRNA. Nicorandil-induced effects were abolished by administering glibenclamide. Similarly, pravastatin-induced beneficial effects were reversed by the addition of glibenclamide, implicating K(ATP) channels as the relevant target. A dissociation between the effects of blood pressure and cardiac structure was noted because pravastatin and hydralazine reduced arterial pressure similarly. These results suggest a crucial role of cardiac K(ATP) channel system in the development of ventricular hypertrophy in the 2K1C hypertensive rats. Pravastatin is endowed with cardiac antihypertrophic properties probably through activation of K(ATP) channels, independent of lipid and hemodynamic changes.  相似文献   

3.
During activation of the renin-angiotensin system, hindbrain circumventricular organs such as the area postrema have been implicated in modulating the arterial baroreflex. This study was undertaken to test the hypothesis that the subfornical organ (SFO), a forebrain circumventricular structure, may also modulate the baroreflex. Studies were performed in rats with two-kidney, one-clip (2K,1C) hypertension as a model of endogenously activated renin-angiotensin system. Baroreflex function was ascertained during ramp infusions of phenylephrine and nitroprusside in conscious sham-clipped and 5-wk 2K,1C rats with either a sham or electrolytically lesioned SFO. Lesioning significantly decreased mean arterial pressure in 2K,1C rats from 158 +/- 7 to 131 +/- 4 mmHg but not in sham-clipped rats. SFO-lesioned, sham-clipped rats had a significantly higher upper plateau and range of the renal sympathetic nerve activity-mean arterial pressure relationship compared with sham-clipped rats with SFO ablation. In contrast, lesioning the SFO in 2K,1C rats significantly decreased both the upper plateau and range of the baroreflex control of renal sympathetic nerve activity, but only the range of the baroreflex response of heart rate decreased. Thus, during unloading of the baroreceptors, the SFO differentially modulates the baroreflex responses in sham-clipped vs. 2K,1C rats. Since lesioning the SFO did not influence plasma angiotensin II (ANG II), the effects of the SFO lesion are not caused by changes in circulating levels of ANG II. These findings support a pivotal role for the SFO in the sympathoexcitation observed in renovascular hypertension and in baroreflex regulation of sympathetic activity in both normal and hypertensive states.  相似文献   

4.
We have previously found that chronic infusion of atrial natriuretic peptide (ANP) decreased mean arterial pressure (MAP) by 16% in two-kidney, one-clip (2K-1C) hypertensive rats, and we hypothesized that natriuresis might be modified through the pressure-natriuresis mechanism. We therefore decided to evaluate sodium balance in 2K-1C rats infused with ANP (0.5 micrograms/h for 4 days). The ANP infusion to the 2K-1C rats induced a significant decrease in MAP from 171 +/- 3 to a minimum value of 147 +/- 6 mm Hg after 2 days of treatment (p less than 0.001). Sodium excretion fell from 2,536 +/- 60 to 2,047 +/- 86 (p less than 0.001) and 2,211 +/- 96 mu Eq/24 h (p less than 0.05) by days 1 and 2 of ANP administration. Furthermore, fractional excretion of sodium intake decreased from 99.1 +/- 1.5 to 81.1 +/- 2.9 (p less than 0.001), 84.1 +/- 2.6 (p less than 0.05) and 85.9 +/- 5.15% (p less than 0.05) by days 1, 2 and 3 of ANP infusion, respectively, returning to basal values thereafter. The administration of vehicle (0.9% NaCl) did not induce any significant change in 2K-1C hypertensive rats. The infusion of either vehicle or the same dose of ANP to normotensive rats (0.5 micrograms/h, for 4 days) did not modify sodium balance throughout the experiment. These results strongly suggest that the ANP-induced decrease in MAP might be responsible for the transitory sodium retention observed in 2K-1C hypertensive rats during the administration of the peptide.  相似文献   

5.
The effect of tetradecylthioacetic acid (TTA) on the cyclooxygenase (COX) system was investigated in two-kidney, one-clip (2K1C) hypertensive rats. The systolic blood pressure (BP) was increased 6 wk after clipping to 183 +/- 4 vs.127 +/- 3 mmHg in TTA-treated 2K1C rats. The COX1 protein expression was not affected either by the 2K1C procedure or by TTA treatment. COX2 expression was upregulated in both kidneys, but to a greater extent in the clipped kidney. COX2 activity was 16 +/- 3% in control and 38 +/- 2% (P < 0.001) in the clipped kidney, and COX2 protein expression was 1.3 +/- 0.04 in control and 1.6 +/- 0.12 in the clipped kidney (P = 0.006). TTA reduced COX2 activity to control levels. Subcutaneously infusion of a COX2 inhibitor did not reduce BP. Peroxisome proliferator-activated receptors (PPARs) were detected in both kidneys, and PPARdelta was upregulated in the nonclipped kidney after TTA treatment. PGE2 in renal cortex was increased in 2K1C (31 +/- 0.3 in the clipped and 28 +/- 0.2 pg/ml nonclipped kidney, P < 0.001 compared with control). TTA lowered the PGE2 to control levels. Renal blood flow (RBF) response to exogenous ANG II injected in the control and nonclipped kidney was exaggerated after indomethacin treatment but unchanged in the nonclipped kidney of the K1C TTA group. Overall, these results indicate that, after 6 wk of treatment, TTA downregulated the COX2 activity, which have potentially important effects on the regulation of renal hemodynamics but does not explain TTAs ability to lower BP.  相似文献   

6.
ABSTRACT: BACKGROUND: Inflammation processes are important participants in the pathophysiology of hypertension and cardiovascular diseases. The role of the alpha7 nicotinic acetylcholine receptor (alpha7nAChR) in inflammation has recently been identified. Our previous study has demonstrated that the alpha7nAChR-mediated cholinergic anti-inflammatory pathway is impaired systemically in the genetic model of hypertension. In this work, we investigated the changes of alpha7nAChR expression in a model of secondary hypertension. METHODS: The 2-kidney 1-clip (2K1C) hypertensive rat model was used. Blood pressure, vagus nerve function, serum tumor necrosis factor-alpha (TNF-alpha) and both the mRNA and protein levels of alpha7nAChR in tissues from heart, kidney and aorta were measured at 4, 8 and 20 weeks after surgery. RESULTS: Compared with age-matched control, it was found that vagus nerve function was significantly decreased in 2K1C rats with the development of hypertension. Serum levels of TNF-alpha were greater in 2K1C rats than in age-matched control at 4, 8 and 20 weeks. alpha7nAChR mRNA in the heart was not altered in 2K1C rats. In the kidney of 2K1C rats, alpha7nAChR expression was significantly decreased at 8 and 20 weeks, but markedly increased at 4 weeks. alpha7nAChR mRNA was less in aorta of 2K1C rats than in age-matched control at 4, 8 and 20 weeks. These findings were confirmed at the protein levels of alpha7nAChR. CONCLUSIONS: Our results suggested that secondary hypertension may induce alpha7nAChR downregulation, and the decreased expression of alpha7nAChR may contribute to inflammation in 2K1C hypertension.  相似文献   

7.
Rats made severely hypertensive by renal arterial clipping were treated for 24 days with the arterial vasodilator minoxidil (40, 80, and 120 mg/L drinking water). In all three treated groups of animals, blood pressure initially decreased markedly and to a similar extent. Subsequently partial tolerance developed to the antihypertensive effects of minoxidil. All three doses induced hypertrophy of the right ventricle to a similar degree. In contrast, the hypertension-induced hypertrophy of the left ventricle was further increased in a dose-dependent fashion by minoxidil.  相似文献   

8.
Presence and release of calcitonin gene-related peptide in rat stomach   总被引:1,自引:0,他引:1  
Immunoreactive (IR)-calcitonin gene-related peptide (CGRP) was identified throughout the entire stomach of rats, being most highly concentrated in the pyloric region, and the concentrations in muscular layers being higher than those in mucosal layers. In addition, IR-CGRP was also present in the venous effluent from isolated perfused rat stomach, and its release was stimulated by dibutyryl cyclic AMP or theophylline but not by glucagon. Gel chromatography as well as HPLC of both tissue extracts and gastric perfusate showed three identical major peaks of IR-CGRP, one of which coeluted with synthetic CGRP. These results suggest that CGRP in the stomach plays a role in the regulation of gastric function.  相似文献   

9.
The systemic cardiovascular and renal effects of synthetic beta-human calcitonin gene-related peptide (beta-hCGRP) were examined in conscious normotensive and one-kidney one-clip (1K-1C) hypertensive dogs. beta-hCGRP was infused intravenously at 10 and 50 ng/kg/min for 75-min periods each. Mean arterial pressure did not change significantly (p greater than 0.05) in either group during low dose infusion of beta-hCGRP, but infusion of beta-hCGRP at 50 ng/kg/min produced a fall in mean arterial pressure from 140 +/- 4 to 116 +/- 6 mmHg (p less than 0.05) in the hypertensive dogs (n = 4) and from 100 +/- 4 to 78 +/- 3 mmHg (p less than 0.05) in the normotensive dogs (n = 4). Heart rates increased significantly during infusion of beta-hCGRP in both groups. Also, renal sodium and potassium excretion decreased (p less than 0.05) in the two groups at both the low and high doses of beta-hCGRP. Creatinine clearance was unchanged in normal dogs and decreased (p less than 0.05) in 1K-1C hypertensive dogs at the high rate of beta-hCGRP infusion. The clearance of p-aminohippurate increased approximately 20% (p less than 0.05) in both groups with the low dose infusion of beta-hCGRP but further increases were elicited only in the normotensive dogs in response to the elevation in the beta-hCGRP infusion rate. Plasma renin and aldosterone levels increased (p less than 0.05) above control levels during the maximum hypotensive response to beta-hCGRP infusion in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
In 2-kidney, 1-clip hypertensive rats, the time course of changes in blood pressure (BP), heart rate, activity of the sympathetic nervous system and the renin-angiotensin system, plasma and blood volumes, left ventricular (LV) and right ventricular (RV) weight, and LV dimensions were evaluated during treatment with hydralazine 80 and 120 mg/L drinking water for 2 days or 1, 2, 3, 5, and 8 weeks. Hydralazine induced initially a clear antihypertensive effect (mean BP from 170-180 down to 135-145 mmHg (1 mmHg = 133.32 Pa], subsequently tolerance developed. Heart rate, plasma catecholamines, and the blood pressure response to hexamethonium were not affected by treatment. Significant increases in plasma renin activity occurred during the initial 1-3 weeks of treatment. Plasma and blood volumes showed only small increases with prolonged treatment. RV weight and LV internal diameter showed significant increases at 3, 5, and 8 weeks of treatment, LV weight at 5 and 8 weeks. LV wall thickness did not change significantly. Thus, treatment with the arterial vasodilator hydralazine causes both RV hypertrophy and eccentric LV hypertrophy. Intravascular volume expansion, associated possibly with redistribution of blood volume to the central compartment, may play a major role in these cardiac effects. Increased renin release but not a generalized increase in sympathetic tone may play a role in the development of tolerance to the antihypertensive effect.  相似文献   

11.
Hemodynamic effects of calcitonin gene-related peptide in conscious rats   总被引:7,自引:0,他引:7  
The cardiovascular effects of calcitonin gene-related peptide (CGRP) were examined in conscious, unrestrained rats. Changes in mean arterial pressure, heart rate and cardiac output were continuously monitored before and after i.v. bolus injection of CGRP (0.1-5 micrograms/kg). Injection of the peptide caused dose-dependent reductions in mean arterial pressure (-24 +/- 4 mmHg), which were accompanied by marked tachycardia. Cardiac output was significantly increased after CGRP but little change was observed in stroke volume. CGRP also reduced total peripheral resistance (-46 +/- 6%). These data indicate that the hypotensive actions of CGRP are mediated through peripheral vasodilation rather than through reductions in cardiac output. Pretreatment with propranolol significantly reduced the tachycardia responses to CGRP from 81 +/- 11 beats/min to 36 +/- 4 beats/min, but did not abolish the increase in heart rate. These data suggest that CGRP produces a tachycardia through reflex increases in cardiac sympathetic tone and through possible direct positive chronotropic effects on the heart.  相似文献   

12.
S J Wimalawansa 《Peptides》1991,12(5):1143-1147
Elevated calcitonin levels in thyroid gland extracts and in plasma accompanied by C-cell hyperplasia are frequently found in old rats, in particular those raised in laboratory conditions. In parallel with calcitonin, we demonstrate here that the thyroidal content and plasma levels of immunoreactive calcitonin gene-related peptide (i-CGRP) significantly increase with age in rats (p less than 0.0001). C18 Sep-Pak-extractable i-CGRP level in plasma was 35% of the total i-CGRP. Gel permeation chromatography and rp-HPLC studies revealed a number of immunoreactive molecular forms of CGRP and only 40-50% of the acid-extracted immunoreactivity was coeluted with the synthetic CGRP(1-37). The i-CGRP level measured in plasma was highly correlated with the thyroidal content of CGRP (p less than 0.001) and also with the age of the rat (p less than 0.001), suggesting an age-related increase of contribution of CGRP from thyroid gland into the circulation.  相似文献   

13.
BackgroudPeperomia pellucida (L.) Kunth has been used widely to treat headache, kidney disease, fever, and hypertension. Previous in vitro studies discovered that the flavonoid-rich extract of this plant has potential hypotensive effects, specifically angiotensin-converting enzyme (ACE)-inhibitory activity. However, there is insufficient scientific evidence to validate the result in vivo.PurposeThis study investigated the dose dependencies of the effects of the ethyl acetate fraction of the ethanolic extract of this plant on blood pressure and biomarkers associated with the renin–angiotensin–aldosterone systems (RAAS), such as angiotensin II (AII) and the plasma renin concentration (PRC).Study designIn total, 30 two-kidney, one-clip (2K1C) hypertensive model rats were divided into five groups (n = 6 each): model group, captopril 25 mg/kg BW group, and three different ethyl acetate groups (25, 50, and 100 mg/kg BW). Another six rats comprised the sham group.MethodsRenal hypertensive rats (RHRs) were generated using stainless steel modification clips. Drugs were administered via oral gavage for 2 consecutive weeks. Blood pressure was measured weekly prior to treatment. Blood samples were collected before treatment and after the last dose to measure AII and PRC. The left kidney was isolated for histopathological examination.ResultsBlood pressure, AII levels, and PRC were elevated after 6 weeks in RHRs. Treatment with captopril and the ethyl acetate fraction of P. pellucida (L.) Kunth decreased blood pressure, AII levels, and PRC. The ethyl acetate fraction at a dose of 50 mg/kg BW had similar ACE-inhibitory effects as captopril. Histopathological examination disclosed coagulative necrosis in clipped kidneys. Impairment was alleviated in a dose-dependent manner by P. pellucida (L.) Kunth, similarly as observed in the captopril group.ConclusionP. pellucida (L.) Kunth targets the renin–angiotensin–aldosterone system, which might explain its antihypertensive effects.  相似文献   

14.
The effects of synthetic human calcitonin gene-related peptide (CGRP) on nociceptive response were evaluated in rats by two behavioral tests (tail-flick and hot-plate) and by electrophysiological recording of the firing of thalamic neurons evoked by peripheral noxious mechanical stimuli. CGRP was administered intracerebroventricularly (i.c.v.) and its effects were compared with that of salmon calcitonin (sCT). In the tail-flick test, CGRP (0.25, 2.5 and 5 micrograms/rat) dose-dependently increased response latencies, whereas sCT (0.125, 2.5, 5 and 10 micrograms/rat) did not. Conversely, in the hot-plate test CGRP was effective in enhancing response latencies only at the highest dose of 10 micrograms/rat, while sCT (0.125, 0.25 and 2.5 micrograms/rat) inhibited the hot-plate response dose-dependently. In electrophysiological studies, CGRP (2.5 micrograms/rat, i.c.v.) completely inhibited the evoked neuronal thalamic firing and the same dose of sCT induced only a partial reduction. Furthermore, the antinociceptive effects of CGRP in the tail-flick test and in the electrophysiological studies were not prevented by naloxone. These results demonstrate that central administration of CGRP is effective in inhibiting nociceptive responses and its action like that of sCT does not involve an opioid mechanism. The differences in the antinociceptive profiles of CGRP and sCT suggest that the inhibitory effects of these peptides may involve different neuronal pathways.  相似文献   

15.
Deng PY  Ye F  Cai WJ  Deng HW  Li YJ 《Regulatory peptides》2004,119(3):155-161
Previous investigations have demonstrated that capsaicin-sensitive sensory nerves are involved in the development of hypertension in some rat models of hypertension. To determine the role played by calcitonin gene-related peptide (CGRP; the predominant neurotransmitter in capsaicin-sensitive sensory nerves) in a rat model of neurogenic hypertension, in which hypertension was induced by injecting 50 microl of 10% phenol in the lower pole of the left kidney, systolic blood pressure (SBP) was monitored by the tail-cuff method throughout the experiment. Fifteen days after injection of phenol, mean arterial pressure (MAP), concentrations of CGRP in the plasma, the expression of CGRP mRNA in dorsal root ganglia (DRG) and CGRP content in laminae I and II of the spinal cord were measured. SBP was significantly increased 5 days after the intrarenal injection of phenol (164+/-7 mm Hg, p<0.01). At the end of experiment, blood pressure (BP) was significantly elevated in the phenol-injected rats compared with the controls (SBP: 187+/-6 vs. 122+/-4 mm Hg, p<0.01; MAP: 157.56+/-3.02 vs. 103.80+/-2.04 mm Hg, p<0.01). Treatment with capsaicin, which selectively depletes neurotransmitters from the capsaicin-sensitive nerves, failed to enhance the development of hypertensive responses to the intrarenal injection of phenol. Intravenous administration of CGRP(8-37), the specific CGRP receptor antagonist, also failed to increase the already elevated MAP. The expression of CGRP mRNA (both alpha- and beta-CGRP isoforms), the content of CGRP in laminae I and II of the dorsal horn of the spinal cord and the concentration of CGRP in the plasma was decreased in the rats treated with phenol. These results suggest that CGRP does not play a counterregulatory role in the phenol-induced hypertensive rats, and support the hypothesis that reduction of CGRP (alpha and beta isoforms) could contribute to a blood pressure elevation in this setting.  相似文献   

16.
In this immunohistochemical study, the ontogenic development of calcitonin-gene-related peptide (CGRP) in the rat thyroid was investigated and compared with that of calcitonin using the indirect-immunofluorescence method. Parafollicular cells with immunoreactivity to both CGRP and calcitonin first appeared at an early stage of gestation (days 17 and 18) in the central portion of the thyroid. Cells immunoreactive to CGRP and calcitonin had became numerous by gestational day 22. After postnatal day 7, CGRP- and calcitonin-immunoreactive (C-IR) cells increased rapidly both in number and in the intensity of their fluorescence. In 14- to 90-day old rats, many intensely immunoreactive cells were distributed in the central portion of the thyroid. The cells immunoreactive to CGRP and to calcitonin had an almost identical ontogenic appearance. In 14-day-old and adult rats, C-IR cells also exhibited CGRP immunostaining, suggesting that these cells simultaneously produce and store CGRP during ontogeny.  相似文献   

17.
Summary In this immunohistochemical study, the ontogenic development of calcitonin-gene-related peptide (CGRP) in the rat thyroid was investigated and compared with that of calcitonin using the indirect-immunofluorescence method. Parafollicular cells with immunoreactivity to both CGRP and calcitonin first appeared at an early stage of gestation (days 17 and 18) in the central portion of the thyroid. Cells immunoreactive to CGRP and calcitonin had became numerous by gestational day 22. After postnatal day 7, CGRP- and calcitonin-immunoreactive (CIR) cells increased rapidly both in number and in the intensity of their fluorescence. In 14- to 90-day old rats, many intensely immunoreactive cells were distributed in the central portion of the thyroid. The cells immunoreactive to CGRP and to calcitonin had an almost identical ontogenic appearance. In 14-day-old and adult rats, C-IR cells also exhibited CGRP immunostaining, suggesting that these cells simultaneously produce and store CGRP during ontogeny.  相似文献   

18.
19.
Nonsteroidal anti-inflammatory drugs have been reported to exacerbate hypertension. In this study, we tested the hypothesis that a nitric oxide-releasing derivative of naproxen would ameliorate hypertension in the rat. Hypertension was induced by partially occluding one renal artery (the "2K,1C" model), and 2 wk later the rats started receiving naproxen, the nitric oxide-releasing derivative HCT-3012, or vehicle each day for 2 wk. Naproxen significantly exacerbated the hypertension. HCT-3012 significantly reduced blood pressure relative to both the naproxen- and vehicle-treated groups. Both naproxen and HCT-3012 markedly suppressed whole blood thromboxane B(2) synthesis. In studies of anesthetized rats, naproxen significantly enhanced the late hypertensive response to endothelin-1 and significantly blunted the early hypotensive response. In contrast, HCT-3102 did not affect either response to endothelin-1. In vitro, HCT-3012 significantly reduced the responsiveness of aortic rings to the contractile effects of phenylephrine. These studies suggest that HCT-3012 reduces blood pressure in hypertensive rats, not simply through the vasodilatory actions of the nitric oxide it releases, but through alterations in the responsiveness of the vasculature to endogenous pressor agents.  相似文献   

20.
Wang X  Sun W  Xing LY  Gong HB  Guo JX 《生理学报》1998,50(2):206-212
我们以前的工作已表明,内毒素可引起降钙素基因相关肽(CGRP)从大鼠肠系膜动脉床释放,此作用部分是通过一氧化氮介导的。我们在离体肠系膜动脉床研究了内毒素引起糖尿病大鼠CCRP释放的改变以及一氧化氮所起的作用。采用CCRP放射免疫分析法测定灌流液中CCRP含量,RT-PCR法测定背根神经节CGRPmRNA水平。结果显示:内毒素累积灌流引起CGRP浓度依赖性地释放增多,此作用在糖尿病大鼠系膜动脉术明显  相似文献   

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