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Zhao Y, Cheng R, Zhao Y, Ge W, Yang Y, Ding Z, Xu X, Wang Z, Wu Z, Zhang J. Type 2 diabetic mice enter a state of spontaneous hibernation-like suspended animation following accumulation of uric acid. J Biol Chem 2021; 297:101166. [PMID: 34487763 PMCID: PMC8484811 DOI: 10.1016/j.jbc.2021.101166] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 08/28/2021] [Accepted: 09/02/2021] [Indexed: 11/25/2022] Open
Abstract
Hibernation is an example of extreme hypometabolic behavior. How mammals achieve such a state of suspended animation remains unclear. Here we show that several strains of type 2 diabetic mice spontaneously enter into hibernation-like suspended animation (HLSA) in cold temperatures. Nondiabetic mice injected with ATP mimic the severe hypothermia analogous to that observed in diabetic mice. We identified that uric acid, an ATP metabolite, is a key molecular in the entry of HLSA. Uric acid binds to the Na+ binding pocket of the Na+/H+ exchanger protein and inhibits its activity, acidifying the cytoplasm and triggering a drop in metabolic rate. The suppression of uric acid biosynthesis blocks the occurrence of HLSA, and hyperuricemic mice induced by treatment with an uricase inhibitor can spontaneously enter into HLSA similar to that observed in type 2 diabetic mice. In rats and dogs, injection of ATP induces a reversible state of HLSA similar to that seen in mice. However, ATP injection fails to induce HLSA in pigs due to the lack of their ability to accumulate uric acid. Our results raise the possibility that nonhibernating mammals could spontaneously undergo HLSA upon accumulation of ATP metabolite, uric acid.
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Affiliation(s)
- Yang Zhao
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China
| | - Rui Cheng
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China
| | - Yue Zhao
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A∗STAR), Singapore
| | - Wenhao Ge
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China
| | - Yunxia Yang
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China
| | - Zhao Ding
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China
| | - Xi Xu
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China
| | - Zhongqiu Wang
- Affiliated Hospital of Nanjing, University of Chinese Medicine, Nanjing, China
| | - Zhenguo Wu
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong, China
| | - Jianfa Zhang
- Center for Molecular Metabolism, Nanjing University of Science & Technology, Nanjing, China.
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Kidoguchi S, Sugano N, Takane K, Takahashi Y, Morisawa N, Yarita M, Hayashi-Ishikawa N, Tokudome G, Yokoo T. Azilsartan causes natriuresis due to its sympatholytic action in kidney disease. Hypertens Res 2019; 42:1507-1517. [PMID: 31138899 DOI: 10.1038/s41440-019-0271-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 04/09/2019] [Accepted: 04/20/2019] [Indexed: 11/09/2022]
Abstract
The sympathoinhibitory mechanism of azilsartan was investigated in an adenine-induced chronic renal failure model. Azilsartan exerted an antihypertensive effect, though BP elevation induced by adenine was marginal. The creatinine value was significantly lower in the azilsartan group (AZ) than in the vehicle group (VEH); furthermore, proteinuria was suppressed, and sodium excretion was augmented in the AZ group. The low frequency (LF) of systolic BP was suppressed (VEH: 4.07 ± 2.67 mmHg2 vs. AZ: 3.32 ± 1.93 mmHg2 P < 0.001), and the spontaneous baroreflex gain (sBRG) was augmented (VEH: 1.04 ± 0.62ms/mmHg vs. AZ: 1.38 ± 0.69 ms/mmHg, P < 0.001) in AZ. There were no significant differences in ACE1 and ACE2 expression between the groups, which indicated that the action of azilsartan on these components of the intrarenal renin-angiotensin-aldosterone system was comparatively small. Although NHE3, NKCC, and ENaC expression was similar between the groups, NaCl cotransporter (NCC) expression was markedly suppressed by azilsartan (P < 0.05). Thus, in a mild chronic kidney disease (CKD) model with slight BP elevation, the sympatholytic effect of ARB might be expected, and azilsartan might exert its natriuretic effect by NCC suppression achieved by sympathoinhibitory activity.
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Affiliation(s)
- Satoshi Kidoguchi
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo, 105-8461, Japan.
| | - Naoki Sugano
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Koki Takane
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Yasuhito Takahashi
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Norihiko Morisawa
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Miki Yarita
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Naomi Hayashi-Ishikawa
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Goro Tokudome
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Takashi Yokoo
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, 3-25-8 Nishi-Shinbashi, Minato-ku, Tokyo, 105-8461, Japan
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Wróblewska M, Kasprzyk J, Sączewski F, Kornicka A, Boblewski K, Lehmann A, Rybczyńska A. Marsanidine and 7-Me-marsanidine, the new hypotensive imidazolines augment sodium and urine excretion in rats. Pharmacol Rep 2013; 65:1025-32. [DOI: 10.1016/s1734-1140(13)71085-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 03/18/2013] [Indexed: 11/26/2022]
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Ferrari F, Fiorentino S, Mennuni L, Garofalo P, Letari O, Mandelli S, Giordani A, Lanza M, Caselli G. Analgesic efficacy of CR4056, a novel imidazoline-2 receptor ligand, in rat models of inflammatory and neuropathic pain. J Pain Res 2011; 4:111-25. [PMID: 21647215 PMCID: PMC3100226 DOI: 10.2147/jpr.s18353] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2011] [Indexed: 12/02/2022] Open
Abstract
Two decades of investigations have failed to unequivocally clarify the functions and the molecular nature of imidazoline-2 receptors (I2R). However, there is robust pharmacological evidence for the functional modulation of monoamino oxidase (MAO) and other important enzyme activities by I2 site ligands. Some compounds of this class proved to be active experimental tools in preventing both experimental pain and opioid tolerance and dependence. Unfortunately, even though these compounds bind with high potency to central I2 sites, they fail to represent a valid clinical opportunity due to their pharmacokinetic, selectivity or side-effects profile. This paper presents the preclinical profile of a novel I2 ligand (2-phenyl-6-(1H-imidazol-1yl) quinazoline; [CR4056]) that selectively inhibits the activity of human recombinant MAO-A in a concentration-dependent manner. A sub-chronic four day oral treatment of CR4056 increased norepinephrine (NE) tissue levels both in the rat cerebral cortex (63.1% ±4.2%; P < 0.05) and lumbar spinal cord (51.3% ± 6.7%; P < 0.05). In the complete Freund’s adjuvant (CFA) rat model of inflammatory pain, CR4056 was found to be orally active (ED50 = 5.8 mg/kg, by mouth [p.o.]). In the acute capsaicin model, CR4056 completely blocked mechanical hyperalgesia in the injured hind paw (ED50 = 4.1 mg/kg, p.o.; ED100 = 17.9 mg/kg, p.o.). This effect was dose-dependently antagonized by the non-selective imidazoline I2/α2 antagonist idazoxan. In rat models of neuropathic pain, oral administration of CR4056 significantly attenuated mechanical hyperalgesia and allodynia. In summary, the present study suggests a novel pharmacological opportunity for inflammatory and/or neuropathic pain treatment based on selective interaction with central imidazoline-2 receptors.
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Affiliation(s)
- Flora Ferrari
- Department of Pharmacology and Toxicology, S.p.A., Monza (MB), Italy
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Nasr MA, El-Gowilly SM, El-Mas MM. Comparable renovascular protective effects of moxonidine and simvastatin in rats exposed to cigarette smoke. Vascul Pharmacol 2010; 53:53-60. [PMID: 20350618 DOI: 10.1016/j.vph.2010.03.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 02/17/2010] [Accepted: 03/22/2010] [Indexed: 01/19/2023]
Abstract
Renovascular impairment plays a major role in smoking-induced nephrotoxicity. This study investigated the effect of the imidazoline I(1)-receptor/alpha(2)-adrenoceptor agonist moxonidine, as compared to the lipid lowering drug simvastatin, on abnormalities induced by cigarette smoke (CS) in renovascular reactivity. Six rat groups were used: control, CS (twice a day for 6weeks), simvastatin, moxonidine, CS+simvastatin, and CS+moxonidine. CS exposure increased plasma urea and creatinine and reduced plasma and renal nitrate/nitrite (NOx). In isolated perfused phenylephrine-preconstricted kidneys of CS rats, vasodilator responses to carbachol or isoprenaline, but not papaverine, were attenuated. Nitric oxide synthase (NOS) inhibition by N(G)-nitro-L-arginine (L-NNA) reduced carbachol vasodilations in control but not CS kidneys, suggesting the impairment of NOS activity by CS. Simultaneous administration of moxonidine or simvastatin abolished CS-induced abnormalities in indices of renal function, NOx, and vasodilations caused by carbachol or isoprenaline. The possibility whether alterations in antioxidant or lipid profiles contributed to the interaction was investigated. CS increased renal malondialdyde and decreased glutathione, and glutathione peroxidase, superoxide dismutase and catalase activities. Further, CS reduced plasma HDL and increased cholesterol, triglycerides, and LDL. Simvastatin or moxonidine abolished the deleterious CS effects on antioxidant activity; the lipid profile was normalized by simvastatin only. These findings highlight that renovascular dysfunction caused by CS and the underlying oxidative damage is evenly attenuated by moxonidine and simvastatin.
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Affiliation(s)
- Magda A Nasr
- Department of Pharmacology, Medical Research Institute, Faculty of Pharmacy, University of Alexandria, Egypt
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El-Ayoubi R, Menaouar A, Gutkowska J, Mukaddam-Daher S. Urinary responses to acute moxonidine are inhibited by natriuretic peptide receptor antagonist. Br J Pharmacol 2005; 145:50-6. [PMID: 15700025 PMCID: PMC1576116 DOI: 10.1038/sj.bjp.0706146] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
We have previously shown that acute intravenous injections of moxonidine and clonidine increase plasma atrial natriuretic peptide (ANP), a vasodilator, diuretic and natriuretic hormone. We hypothesized that moxonidine stimulates the release of ANP, which would act on its renal receptors to cause diuresis and natriuresis, and these effects may be altered in hypertension. Moxonidine (0, 10, 50, 100 or 150 microg in 300 microl saline) and clonidine (0, 1, 5 or 10 microg in 300 microl saline) injected intravenously in conscious normally hydrated normotensive Sprague-Dawley rats (SD, approximately 200 g) and 12-14-week-old Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) dose-dependently stimulated diuresis, natriuresis, kaliuresis and cGMP excretion, with these effects being more pronounced during the first hour post-injection. The actions of 5 microg clonidine and 50 microg moxonidine were inhibited by yohimbine, an alpha2-adrenoceptor antagonist, and efaroxan, an imidazoline I1-receptor antagonist. Moxonidine (100 microg) stimulated (P<0.01) diuresis in SHR (0.21+/-0.04 vs 1.16+/-0.06 ml h(-1) 100 g(-1)), SD (0.42+/-0.06 vs 1.56+/-0.19 ml h(-1) 100 g(-1)) and WKY (0.12+/-0.04 vs 1.44+/-0.21 ml h(-1) 100 g(-1)). Moxonidine-stimulated urine output was lower in SHR than in SD and WKY. Moxonidine-stimulated sodium and potassium excretions were lower in SHR than in SD, but not WKY, demonstrating an influence of strain but not of pressure. Pretreatment with the natriuretic peptide antagonist anantin (5 or 10 microg) resulted in dose-dependent inhibition of moxonidine-stimulated urinary actions. Anantin (10 microg) inhibited (P<0.01) urine output to 0.38+/-0.06, 0.12+/-0.01, and 0.16+/-0.04 ml h(-1) 100 g(-1) in SD, WKY, and SHR, respectively. Moxonidine increased (P<0.01) plasma ANP in SD (417+/-58 vs 1021+/-112 pg ml(-1)) and WKY (309+/-59 vs 1433+/-187 pg ml(-1)), and in SHR (853+/-96 vs 1879+/-229 pg ml(-1)). These results demonstrate that natriuretic peptides mediate the urinary actions of moxonidine through natriuretic peptide receptors.
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Affiliation(s)
- Rouwayda El-Ayoubi
- Laboratory of Cardiovascular Biochemistry, Centre hospitalier de l'Université de Montréal-Hotel-Dieu, and Department of Medicine, Université de Montréal, Montreal (Quebec), Canada
| | - Ahmed Menaouar
- Laboratory of Cardiovascular Biochemistry, Centre hospitalier de l'Université de Montréal-Hotel-Dieu, and Department of Medicine, Université de Montréal, Montreal (Quebec), Canada
| | - Jolanta Gutkowska
- Laboratory of Cardiovascular Biochemistry, Centre hospitalier de l'Université de Montréal-Hotel-Dieu, and Department of Medicine, Université de Montréal, Montreal (Quebec), Canada
| | - Suhayla Mukaddam-Daher
- Laboratory of Cardiovascular Biochemistry, Centre hospitalier de l'Université de Montréal-Hotel-Dieu, and Department of Medicine, Université de Montréal, Montreal (Quebec), Canada
- Author for correspondence:
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Jovanovska V, Eitle E, Harris PJ. EFFECTS OF RILMENIDINE ON PROXIMAL TUBULAR FLUID ABSORPTION IN RATS. Clin Exp Pharmacol Physiol 2004; 31:348-53. [PMID: 15191410 DOI: 10.1111/j.1440-1681.2004.04008.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The antihypertensive agent rilmenidine has threefold higher affinity for I(1) imidazoline receptors compared with alpha(2)-adrenoceptors and acts on the central nervous system by reducing sympathetic activity and in the kidney by inhibiting Na(+)/H(+) exchange activity. In the present study, we examined: (i) the effects of luminal and peritubular administration of rilmenidine on fluid absorption in superficial proximal tubules; and (ii) the nature of the receptors involved in mediating the action of this drug in the presence of specific antagonists (efaroxan, idazoxan and 2-methoxy-idazoxan). Studies were performed in anaesthetized Sprague-Dawley rats using shrinking split-drop micropuncture. Luminal administration of rilmenidine (10(-5) and 10(-13) mol/L) inhibited proximal tubular fluid absorption. Peritubular rilmenidine at 10(-12) and 10(-13) mol/L also inhibited fluid uptake, whereas rilmenidine at 10(-11) mol/L had a significant stimulatory action. In the presence of the I(2) > I(1)/alpha(2)-adrenoceptor antagonist idazoxan (10(-5) mol/L), luminal rilmenidine (10(-5) mol/L) stimulated fluid absorption. Stimulation of fluid uptake was also observed when rilmenidine (10(-5) mol/L) and the I(1) imidazoline receptor antagonist efaroxan (10(-5) mol/L) were added together in the luminal fluid. Luminal administration of the selective alpha(2)-adrenoceptor antagonist 2-methoxy-idazoxan (10(-5) mol/L) resulted in significant attenuation of the inhibitory action of luminal rilmenidine (10(-5) mol/L). This indicates that both I(1) imidazoline receptors and alpha(2)-adrenoceptors are involved in the luminal actions of rilmenidine. The effects of luminal and peritubular administration of alpha-methylnoradrenaline (an alpha(2)-adrenoceptor agonist) were compared with those of rilmenidine. Luminal alpha-methylnoradrenaline, at higher concentrations (10(-7) and 10(-5) mol/L), inhibited fluid absorption, as was seen with peritubular rilmenidine, but, in contrast with rilmenidine, no stimulatory action was observed. Peritubular alpha-methylnoradrenaline inhibited fluid uptake at higher concentrations (10(-5) and 10(-7) mol/L), whereas rilmenidine at these concentrations had no effect. The differences in the concentration-dependent responses for rilmenidine and alpha-methylnoradrenaline indicate that both imidazoline receptors and alpha(2)-adrenoceptors are involved in the actions of these compounds on proximal fluid uptake.
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Affiliation(s)
- Valentina Jovanovska
- Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia
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Cetinkaya I, Schlatter E, Hirsch JR, Herter P, Harms E, Kleta R. Inhibition of Na(+)-dependent transporters in cystine-loaded human renal cells: electrophysiological studies on the Fanconi syndrome of cystinosis. J Am Soc Nephrol 2002; 13:2085-93. [PMID: 12138140 DOI: 10.1097/01.asn.0000023681.13865.25] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Cystinosis is the most common cause of the renal Fanconi syndrome in children, leading to severe electrolyte disturbances and growth failure. A defective lysosomal transporter, cystinosin, results in intralysosomal accumulation of cystine. Loading cells with cystine dimethyl ester (CDME) is the only available model for this disease. This model was used to present electrophysiologic studies on immortalized human kidney epithelial (IHKE-1) cells that had been derived from the proximal tubule with the slow whole-cell patch clamp technique. Basal membrane voltages (V(m)) of IHKE-1 cells were -30.7 +/- 0.4 mV (n = 151). CDME concentration-dependently altered V(m) with an initial depolarization (2.7 +/- 0.2 mV;n = 76; 1 mM CDME) followed by a more pronounced hyperpolarization (-9.9 +/- 1.0 mV;n = 49). Three Na(+)-dependent transporters were examined. Alanine (1 mM) depolarized IHKE-1 cells by 17.6 +/- 0.7 mV (n = 59), and phosphate (1.8 mM) depolarized by 9.7 +/- 1.1 mV (n = 18). Acidification of IHKE-1 cells with propionate (20 mM) resulted in a depolarization of V(m) by 7.1 +/- 0.3 mV (n = 21) followed by a repolarization by 2.9 +/- 0.3 mV/min (n = 17), reflecting Na(+)/H(+)-exchanger activity. Acute addition of 1 mM CDME did not alter the alanine- and propionate-induced changes in V(m), but it reduced the phosphate-induced depolarization by 37 +/- 9% (n = 10). Incubation with 1 mM CDME reduced the activity of all three transporters. Depolarizations by alanine and phosphate and the repolarization after propionate were inhibited by 57 +/- 4% (n =30), 45 +/- 9% (n = 9), and 78 +/- 15% (n = 8), respectively. In conclusion, this study demonstrates that CDME acutely alters V(m) of IHKE-1 cells and that at least three Na(+)-dependent transporters are inhibited, the Na(+)-phosphate cotransporter most sensitively. This might suggest that phosphate depletion and dissipation of the Na(+)-gradient are involved in the development of the Fanconi syndrome of cystinosis.
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Affiliation(s)
- Ibrahim Cetinkaya
- Department of Pediatrics, University Children's Hospital Muenster, Muenster, Germany
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9
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Abstract
Initially it was considered that moxonidine, like clonidine, acted at central (2)-adrenoceptors to reduce blood pressure. With the characterisation of imidazoline binding sites distinct from (2)-adrenoceptors, the consensus became that moxonidine was acting predominantly at imidazoline I(1) receptors in the rostral ventrolateral medulla to lower blood pressure. Moxonidine acts at prejunctional (2)-adrenoceptors on sympathetic nerve endings to decrease noradrenaline release and this may contribute to its ability to lower blood pressure. The predominant site of action of moxonidine may also depend on route of administration, with imidazoline I(1) receptors being predominant after central, and (2)-adrenoceptors predominant after systemic administration. The controversy over the mechanism and site of action with moxonidine is ongoing. In animal models, moxonidine lowers blood pressure, reduces cardiac hypertrophy and remodelling, reduces cardiac arrhythmias and increases blood flow in cerebral ischaemia. Moxonidine also has beneficial effects in animal models of diabetes and kidney disease. Moxonidine increases sodium and water excretion in rats, but not humans. Animal studies indicate that moxonidine may be useful in the treatment of glaucoma by reducing intra-ocular pressure. Animal studies show that moxonidine may also be effective in pain and in ethanol withdrawal. In humans, the pharmacokinetics of moxonidine are of the one-compartment model with first-order absorption. Renal elimination is the major route of elimination and individual titration of moxonidine is needed in patients with renal impairment. There is overwhelming evidence that moxonidine is a safe and effective antihypertensive. A large clinical trial of moxonidine in heart failure, MOXCON, was stopped because of excessive deaths in the moxonidine group. Moxonidine should not be used in patients with heart failure, but there are no obvious reasons to stop its use as an antihypertensive, or its development for other clinical uses.
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Affiliation(s)
- S A Doggrell
- Doggrell Biomedical Communications, 47 Caronia Crescent, Lynfield, Auckland, New Zealand
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Rump LC, Amann K, Orth S, Ritz E. Sympathetic overactivity in renal disease: a window to understand progression and cardiovascular complications of uraemia? Nephrol Dial Transplant 2000; 15:1735-8. [PMID: 11071955 DOI: 10.1093/ndt/15.11.1735] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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11
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Amann K, Rump LC, Simonaviciene A, Oberhauser V, Wessels S, Orth SR, Gross ML, Koch A, Bielenberg GW, VAN Kats JP, Ehmke H, Mall G, Ritz E. Effects of low dose sympathetic inhibition on glomerulosclerosis and albuminuria in subtotally nephrectomized rats. J Am Soc Nephrol 2000; 11:1469-1478. [PMID: 10906160 DOI: 10.1681/asn.v1181469] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
ABSTRACT.: A potential role of the sympathetic nervous system in progression of renal failure has received little attention. This study examined whether nonhypotensive doses of moxonidine, an agent that reduces sympathetic activity, affects glomerulosclerosis, urine albumin excretion, and indices of renal handling of norepinephrine (NE) in subtotally nephrectomized (SNX) rats. Sprague Dawley rats were SNX or sham-operated (control). SNX rats were either left untreated or treated with moxonidine in a dose (1.5 mg/kg body wt per d) that did not modify telemetrically monitored 24-h BP. Glomerular and renal morphology were evaluated by quantitative histology, immunohistochemistry, and in situ hybridization. Urine albumin excretion rate was analyzed by enzyme-linked immunosorbent assay, and kidney angiotensin II and NE content were measured using HPLC, (3)H-NE uptake, and release. Body and kidney weight and BP were not significantly different between SNX with or without moxonidine. The glomerulosclerosis index was significantly lower in moxonidine-treated (0.88 +/- 0.09) compared with untreated (1.55 +/- 0.28) SNX rats, as was the index of vascular damage (0.32 +/- 0.14 versus 0.67 +/- 0.16). The number of proliferating cell nuclear antigen-positive glomerular and tubular cells per area was significantly higher in untreated SNX rats than in controls and moxonidine-treated SNX rats. The same was true for urine albumin excretion rate. Renal angiotensin II tissue concentration was not affected by moxonidine. In untreated SNX rats, renal nerve stimulation and exogenous NE induced an increase in isolated kidney perfusion pressure (102 +/- 21 versus 63 +/- 8 mmHg). Renal endogenous NE content was significantly lower in SNX rats than in controls (86 +/- 14 versus 140 +/- 17 pg/mg wet weight). Cortical uptake of [(3)H]-NE was not different, but cortical NE release was significantly higher in SNX rats than in controls. Reduced function of presynaptic inhibitory alpha-adreno-receptors is unlikely because an alpha(2)-adrenoceptor antagonist increased NE release. At subantihypertensive doses, moxonidine ameliorates renal structural and functional damage in SNX animals, possibly through central inhibition of efferent sympathetic nerve traffic. In kidneys of SNX rats, indirect evidence was found for increased activity of a reduced number of nerve fibers.
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Affiliation(s)
- Kerstin Amann
- Department of Pathology, University of Heidelberg, Germany
- Department of Pathology, University of Erlangen-Nürnberg, Germany
| | | | | | - Vitus Oberhauser
- Department of Internal Medicine IV, University of Freiburg, Germany
| | - Sabine Wessels
- Department of Pathology, University of Heidelberg, Germany
| | - Stephan R Orth
- Department of Internal Medicine, University of Heidelberg, Germany
| | | | - Andreas Koch
- Department of Pathology, University of Heidelberg, Germany
| | | | - Jorge P VAN Kats
- Department of Internal Medicine, Erasmus University, Rotterdam, The Netherlands
| | - Heimo Ehmke
- Department of Physiology, University of Hamburg, Germany
| | | | - Eberhard Ritz
- Department of Internal Medicine, University of Heidelberg, Germany
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Abstract
On the basis of both radioligand and functional studies, the existence of a novel receptor that was unique from the alpha 2-adrenoceptor has become evident. Our initial studies contrasted the function of I1 imidazoline receptor agonists with that of purported alpha 2-adrenoceptor agonists in the kidney. The mechanism by which urine flow increased (osmolar vs free water clearance) as well as the effects of idazoxan, rauwolscine, a V2 vasopressin receptor antagonist, indomethacin pretreatment, and one-kidney one clip hypertension in rats were different following moxonidine when compared to an alpha 2-adrenoceptor agonist. This indicated two separate receptor systems. Subsequent studies determined that i.c.v. administration of moxonidine would also increase the urine flow rate by increasing osmolar clearance. This response to i.c.v. moxonidine differed from the response of an alpha 2-adrenoceptor agonist administered i.c.v.. Moreover, this effect of i.c.v. moxonidine was unique from that observed following the intrarenal infusion of moxonidine (Fig. 2). Denervation, intravenous prazosin, and i.c.v. idazoxan selectively blocked the effects of i.c.v. moxonidine. Intravenous idazoxan selectively blocked the response to intrarenal infusion of moxonidine. On the basis of the response to i.c.v. moxonidine in SH rats, the site(s) and/or receptor(s) responsible for blood pressure lowering were altered and those for increasing sodium excretion appear to be inactive. The significance of the findings in long-term regulation of blood pressure remain to be determined.
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Affiliation(s)
- D D Smyth
- Department of Pharmacology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
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Ekelund U, Björnberg J, Mellander S. Alpha 2-adrenoceptor activation may trigger the increased production of endothelium-derived nitric oxide in skeletal muscle during acute haemorrhage. ACTA PHYSIOLOGICA SCANDINAVICA 1998; 164:285-92. [PMID: 9853016 DOI: 10.1046/j.1365-201x.1998.00438.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Our previous studies indicated that acute haemorrhage leads to a pronounced increase in the release of endothelium-derived nitric oxide (EDNO) graded in relation to the magnitude of the blood loss. The EDNO-induced vasodilatation, confined selectively to the arterial 'feeder' vessels, attenuates the concomitant reflex adrenergic constriction and thereby prevents deleterious reduction of blood flow. The present study aimed at investigating whether the reflex release of blood-borne catecholamines might trigger this EDNO release via activation of endothelial alpha 2-adrenoceptors. The study was performed on the sympathectomized vascular bed of cat skeletal muscle with a technique permitting quantitative recordings of resistance (tone) in consecutive vascular sections. Selection alpha 2-adrenoceptor blockade with idazoxan applied at steady state vasoconstriction after a 35% blood loss evoked an initial generalized dilator response (attributable to inhibition of post-synaptic smooth muscle alpha 2-adrenoceptors), followed by a constrictor response selectively in the arterial feeder vessels, the latter compatible with the hypothesis of reduced EDNO release by alpha 2-adrenoceptor blockade. More direct evidence for the hypothesis was obtained from studies of the vascular response to EDNO blockade (L-NAME) after haemorrhage in the presence and absence of alpha 2-adrenoceptor blockade. The constrictor response to EDNO blockade, which is a measure of the pre-existing EDNO dilator influence (EDNO production), was significantly smaller (P < 0.01) in the presence than absence of alpha 2-adrenoceptor blockade. The results indicate that blood-borne catecholamines, via activation of endothelial alpha 2-adrenoceptors, trigger the increase in the EDNO release in acute haemorrhage, implying a functionally important negative feedback in the integrated control of vascular tone in bleeding.
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MESH Headings
- Acute Disease
- Adrenergic alpha-2 Receptor Antagonists
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Cats
- Clonidine/pharmacology
- Epinephrine/blood
- Hemorrhage/enzymology
- Idazoxan/pharmacology
- Male
- Muscle, Skeletal/blood supply
- Muscle, Skeletal/enzymology
- Muscle, Smooth, Vascular/blood supply
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- NG-Nitroarginine Methyl Ester/pharmacology
- Nitric Oxide Synthase/antagonists & inhibitors
- Nitric Oxide Synthase/metabolism
- Nitric Oxide Synthase Type III
- Norepinephrine/blood
- Receptors, Adrenergic, alpha-2/metabolism
- Regional Blood Flow/drug effects
- Regional Blood Flow/physiology
- Vasodilation/drug effects
- Vasodilation/physiology
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Affiliation(s)
- U Ekelund
- Department of Physiology & Neuroscience, University of Lund, Sweden
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