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Carter CS, Groban L. Role of the renin-angiotensin system in age-related sarcopenia and diastolic dysfunction. ACTA ACUST UNITED AC 2008; 4:37-46. [PMID: 20445808 DOI: 10.2217/1745509x.4.1.37] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The purpose of this review is to describe how recent pharmacological and genetic studies have contributed to our understanding of the role of the renin-angiotensin system (RAS) in age-related sarcopenia and diastolic dysfunction. Treatment strategies are limited in the context of both of these conditions, although interventions, which include blockade of the RAS (using angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers) are successful and lead to improvements in functional outcomes that are not necessarily mediated by hemodynamic effects of the drugs. Studies in animal models of sarcopenia and diastolic dysfunction point to ubiquitous effects of RAS blockade on multiple biological mechanisms, including inflammation, oxidative damage and metabolic dysregulation. Therefore, a re-evaluation of the use of these drugs in other conditions should be considered for maintaining functional independence in older individuals.
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Affiliation(s)
- Christy S Carter
- University of Florida, Department of Aging & Geriatric Research, 1329 SW 16th Street, Room 5274, PO Box 100143, Gainesville, FL 32610-0143, USA, Tel.: +1 352 273 5727
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2
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Tomioka S, Ogata H, Tamura Y, Shimizu T, Watada H, Fujitani Y, Kawamori R, Hirose T. Clinical characteristics influencing the effectiveness of metformin on Japanese type 2 diabetes receiving sulfonylureas. Endocr J 2007; 54:247-53. [PMID: 17303931 DOI: 10.1507/endocrj.k06-162] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In this study, we described the effectiveness of metformin on Japanese type 2 diabetes patients receiving sulfonylureas and the clinical characteristics of the patients whose glycemic control were significantly improved with metformin administration. Our results showed that the reduction of glycohemoglobin (HbA1C), serum concentration of total cholesterol, and diastolic blood pressure was statistically significant through the administration of metformin. The clinical characteristics of the patients who responded to metformin therapy exhibited lower systolic blood pressure in addition to higher HbA1C value just before administration of metformin when compared with DeltaHbA1C (HbA1C 6 months after administration of metformin--HbA1C before administration of metformin). Moreover, effectiveness of metformin was weakened, in comparison with non-hypertensive patients, even though the blood pressure of hypertensive patients was reduced to normal range by medication with antihypertensive drugs. But average reduction of HbA1C level of hypertensive patients without antihypertensive medications was smaller than those of patients with high blood pressure with such medication. These results suggested that high blood pressure and hypertension phenotype itself were suppressive factors of metformin but antihypertensive therapy itself enhanced the effectiveness of metformin regardless of the improvement of blood pressure.
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Affiliation(s)
- Setsuko Tomioka
- Clinical Pharmacy Course, Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, Japan
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Cahová M, Vavrinková H, Tutterova M, Meschisvilli E, Kazdova L. Captopril enhanced insulin-stimulated glycogen synthesis in skeletal muscle but not fatty acid synthesis in adipose tissue of hereditary hypertriglyceridemic rats. Metabolism 2003; 52:1406-12. [PMID: 14624398 DOI: 10.1016/s0026-0495(03)00319-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In addition to their hypotensive action, angiotensin-converting enzyme (ACE) inhibitors exert a beneficial effect on glucoregulation. In the present study, the effect of ACE inhibition by captopril on glucose utilization in peripheral tissues was investigated in non-obese rats with hereditary hypertriglyceridemia (HHTg) associated with hyperinsulinemia and insulin resistance. Normotriglyceridemic Wistar rats served as controls (C). Rats of both groups received a high-sucrose diet, and a half of each group also captopril in drinking water (10 mg/kg body weight [bw]) for 2 weeks. Captopril administration reduced fasting glycemia and postprandial triglyceridemia in HHTg rats, while the fasting levels of nonesterified fatty acids (NEFA), glycerol, and lactate were decreased in both groups. The sensitivity of skeletal muscle to insulin action evaluated as in vitro 14C-glucose incorporation into glycogen was significantly increased by captopril treatment both in HHTg (3.51 +/- 0.48 v 2.0 +/- 0.12 micromol glucose/g wet weight [ww]) and C (3.32 +/- 0.21 v 2.48 +/- 0.09 micromol glucose/g ww). In isolated adipose tissue, the insulin-stimulated 14C-glucose incorporation into neutral lipids was increased, after captopril administration, by 137% in C and by 35% only in HHTg. After captopril treatment, insulin-stimulated de novo fatty acid synthesis rose significantly in C while remaining low in HHTg. The increase in esterification was comparable in both groups. Separate experiments were designed to assess the possible involvement of bradykinin in mediating captopril action. Both C and HHTg rats fed a high-sucrose diet for 2 weeks were treated with captopril (50 mg/kg orally) for 1 hour; half of each group received the specific inhibitor of bradykinin receptor HOE-140 (100 microg/kg intraperitoneally [i.p.]) 1 hour before captopril administration. In C, captopril administration enhanced the insulin-stimulated in vitro glucose incorporation into lipids in adipose tissue by 255%, and into glycogen in the musculus soleus by 45%; this effect was eliminated by HOE-140. In HHTg, neither a single dose of captopril nor HOE-140 had any effect. We conclude that long-term captopril administration increased the insulin sensitivity of peripheral tissue in both C and HHTg rats, but with different efficacy. While the insulin-sensitizing action of captopril on skeletal muscle was comparable in HHTg and C rats, there were differences in the effect of captopril on adipose tissue. The difference became particularly manifest in de novo fatty acid synthesis.
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Affiliation(s)
- Monika Cahová
- Department of Metabolic Research, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
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Henriksen EJ, Jacob S. Modulation of metabolic control by angiotensin converting enzyme (ACE) inhibition. J Cell Physiol 2003; 196:171-9. [PMID: 12767053 DOI: 10.1002/jcp.10294] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Angiotensin converting enzyme (ACE) inhibitors are a widely used intervention for blood pressure control, and are particularly beneficial in hypertensive type 2 diabetic subjects with insulin resistance. The hemodynamic effects of ACE inhibitors are associated with enhanced levels of the vasodilator bradykinin and decreased production of the vasoconstrictor and growth factor angiotensin II (ATII). In insulin-resistant conditions, ACE inhibitors can also enhance whole-body glucose disposal and glucose transport activity in skeletal muscle. This review will focus on the metabolic consequences of ACE inhibition in insulin resistance. At the cellular level, ACE inhibitors acutely enhance glucose uptake in insulin-resistant skeletal muscle via two mechanisms. One mechanism involves the action of bradykinin, acting through bradykinin B(2) receptors, to increase nitric oxide (NO) production and ultimately enhance glucose transport. A second mechanism involves diminution of the inhibitory effects of ATII, acting through AT(1) receptors, on the skeletal muscle glucose transport system. The acute actions of ACE inhibitors on skeletal muscle glucose transport are associated with upregulation of insulin signaling, including enhanced IRS-1 tyrosine phosphorylation and phosphatidylinositol-3-kinase activity, and ultimately with increased cell-surface GLUT-4 glucose transporter protein. Chronic administration of ACE inhibitors or AT(1) antagonists to insulin-resistant rodents can increase protein expression of GLUT-4 in skeletal muscle and myocardium. These data support the concept that ACE inhibitors can beneficially modulate glucose control in insulin-resistant states, possibly through a NO-dependent effect of bradykinin and/or antagonism of ATII action on skeletal muscle.
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Affiliation(s)
- Erik J Henriksen
- Muscle Metabolism Laboratory, Department of Physiology, University of Arizona College of Medicine, Tucson, Arizona 85721-0093, USA.
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Henriksen EJ, Jacob S. Angiotensin converting enzyme inhibitors and modulation of skeletal muscle insulin resistance. Diabetes Obes Metab 2003; 5:214-22. [PMID: 12795654 DOI: 10.1046/j.1463-1326.2003.00265.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- E J Henriksen
- Muscle Metabolism Laboratory, Department of Physiology, University of Arizona College of Medicine, Tucson, AZ 85721-0093, USA
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Moisés RS, Carvalho CRO, Shiota D, Saad MJA. Evidence for a direct effect of captopril on early steps of insulin action in BC3H-1 myocytes. Metabolism 2003; 52:273-8. [PMID: 12647262 DOI: 10.1053/meta.2003.50044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Captopril, an angiotensin-converting enzyme (ACE) inhibitor, has been reported to improve insulin sensitivity. However, despite extensive investigation, the mechanisms responsible for this effect are not fully understood. Reduction of plasma angiotensin II and inhibition of kininase II have been suggested to contribute to improve insulin sensitivity. Insulin binding was measured at tracer insulin concentration in intact cells with or without captopril treatment. Specific binding, expressed as percent of total insulin added, was not different in control and captopril-treated cells. However, captopril treatment caused an increase in insulin-induced insulin receptor substrate-1 (IRS-1) phosphorylation accompanied by an increased association of IRS-1 with phosphoinositide-3 kinase (PI-3 kinase), despite no change on insulin receptor (IR) autophosphorylation. There was also an increased threonine kinase B (AKT) phosphorylation in captopril-treated cells followed by enhanced basal and insulin-stimulated glucose uptake. These results indicate that captopril treatment has a direct effect on early phosphorylation events induced by insulin in BC3H-1 myocytes.
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Affiliation(s)
- Regina S Moisés
- Disciplina de Endocrinologia, Universidade Federal de São Paulo, Escola Paulista de Medicina, São Paulo, Brazil
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Patel VB, Richardson PJ, Preedy VR. Non-cardiac nucleic acid composition and protein synthesis rates in hypertension: studies on the spontaneously hypertensive rat (SHR) model. Clin Chim Acta 2000; 293:167-79. [PMID: 10699431 DOI: 10.1016/s0009-8981(99)00243-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Various studies have shown the involvement of extracardiac tissues in hypertension, including the hepato-intestinal tract, musculo-skeletal system, skin, and the kidney. It was our hypothesis that these perturbations in non-cardiac tissues would also include alterations in protein metabolism. Thus, the reported differences in soleus contractile protein composition may be related to changes in muscle protein synthesis or reduced protein synthetic efficiencies. The aim of the present study was to characterise tissue composition of nucleic acids and rates of protein synthesis in non-cardiac tissues, such as liver, skeletal muscle (i.e., the Type I fibre-predominant soleus and Type II fibre-predominant plantaris), kidney, bone (tibia), skin and the gastrointestinal tract in a genetic model of hypertension (i.e., spontaneously hypertensive rats (SHRs), 15 weeks old) compared to their genetic aged-matched counterparts, i.e., normotensive Wistar-Kyoto (WKY) controls. Rates of protein synthesis were measured in vivo after injection with a flooding dose of L-[4-(3)H]phenylalanine. The results showed changed tissue wet weights (g per organ) for plantaris (+10%, P<0.05), liver (+25%, P<0.01), brain (-9%, P<0.01), jejunum (+39%, P<0.001) and tibia (+17%, P<0.001) in SHRs compared to WKY controls. Protein content (g or mg per organ) was increased in the liver (+32%, P<0. 01) and tibia (+37%, P<0.05). RNA contents (mg per organ) were increased in plantaris (+17%, P<0.01), liver (+22%, P<0.01) and jejunum (+11%, P<0.05). DNA (mg per organ) was increased in plantaris (+16%, P<0.025) and jejunum (+12%, P<0.025). The protein synthetic capacities (i.e., C(s), mg RNA/g protein) were higher in soleus (+41%, P<0.01) and plantaris (+6%, P<0.05) muscles of SHRs compared to WKYs, whereas values were lower in liver (-11%, P<0.01) and kidney (-6%, P<0.01) of SHRs compared to WKYs. The fractional rate of protein synthesis (i.e., k(s), the percentage of the protein pool renewed each day) was not significantly different for any of the tissues, though the rate of protein synthesis per unit RNA (i.e., k(RNA), mg protein/day per mg RNA) was reduced in the soleus (-24%, P<0.05) and the synthesis rate per unit DNA, i.e., k(DNA) (mg protein/day per mg DNA) was increased in the tibia (+31%, P<0.025). This is the first report of significant differences between indices of protein metabolism in extracardiac tissues in hypertension, which may reflect endocrine factors and/or the systemic influence of hypertension per se.
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Affiliation(s)
- V B Patel
- Department of Clinical Biochemistry, Guy's, King's and St Thomas's School of Medicine, King's College, London, UK
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Henriksen EJ, Jacob S, Kinnick TR, Youngblood EB, Schmit MB, Dietze GJ. ACE inhibition and glucose transport in insulinresistant muscle: roles of bradykinin and nitric oxide. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:R332-6. [PMID: 10409290 DOI: 10.1152/ajpregu.1999.277.1.r332] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acute administration of the angiotensin-converting enzyme (ACE) inhibitor captopril enhances insulin-stimulated glucose transport activity in skeletal muscle of the insulin-resistant obese Zucker rat. The present study was designed to assess whether this effect is mediated by an increase in the nonapeptide bradykinin (BK), by a decrease in action of ANG II, or both. Obese Zucker rats (8-9 wk old) were treated for 2 h with either captopril (50 mg/kg orally), bradykinin (200 micrograms/kg ip), or the ANG II receptor (AT(1) subtype) antagonist eprosartan (20 mg/kg orally). Captopril treatment enhanced in vitro insulin-stimulated (2 mU/ml) 2-deoxyglucose uptake in the epitrochlearis muscle by 22% (251 +/- 7 vs. 205 +/- 9 pmol. mg(-1). 20 min(-1); P < 0.05), whereas BK treatment enhanced this variable by 18% (249 +/- 15 vs. 215 +/- 7 pmol. mg(-1). 20 min(-1); P < 0.05). Eprosartan did not significantly modify insulin action. The BK-mediated increase in insulin action was completely abolished by pretreatment with either the specific BK-B(2) receptor antagonist HOE 140 (200 micrograms/kg ip) or the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (50 mg/kg ip). Collectively, these results indicate that the modulation of insulin action by BK likely underlies the metabolic effects of ACE inhibitors in the insulin-resistant obese Zucker rat. Moreover, this modulation of insulin action by BK is likely mediated through B(2) receptors and by an increase in nitric oxide production and/or action in skeletal muscle tissue.
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Affiliation(s)
- E J Henriksen
- Muscle Metabolism Laboratory, Department of Physiology, University of Arizona College of Medicine, Tucson, Arizona 85721-0093, USA.
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9
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Miatello RM, Damiani MT, Nolly HL. Cardiovascular kinin-generating capability in hypertensive fructose-fed rats. J Hypertens 1998; 16:1273-7. [PMID: 9746114 DOI: 10.1097/00004872-199816090-00008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The hypertensive state is often associated with metabolic abnormalities, including glucose intolerance. Tissue kallikrein, a potent kinin-generating enzyme, is present in the vascular wall and heart tissue. High dietary fructose consumption is reported to induce hyperinsulinemia, hypertriglyceridemia and hypertension. The objective of the present study was to examine the status of kallikrein in vascular and cardiac tissue from highly fructose-fed rats and to delineate the effect of kinins and the angiotensin converting enzyme inhibitor ramipril in this animal model of glucose intolerance. DESIGN AND METHODS Male Wistar rats (350 g body weight) were divided into four groups of 10 rats each: (1) controls; (2) oral ramipril at 500 microg/kg per day for the last 2 study weeks; (3) fructose in drinking water as a 10% (w/v) solution for 4 weeks; and (4) fructose + ramipril, with fructose administered as in group 3 plus the administration of ramipril for the last 2 study weeks. Systolic blood pressure (tail-cuff method), glucose tolerance (2 g/kg body weight intraperitoneally) and metabolic parameters were recorded. Kallikrein activity in tail artery and heart tissue homogenates was estimated at the end of the 4th study week from measurements of kininogenase activity and kinins generated by a radioimmunoassay. RESULTS The area under the curve for the glucose tolerance test increased from 1265 +/- 103 mmol/l after 120 min in the control and 1152 +/- 36 mmol/l in the ramipril group (NS) to 2628 +/- 143 mmol/l in the fructose group (P<0.01). The administration of ramipril to fructose-treated rats in group 4 improved glucose tolerance (2160 +/- 100 mmol/l; P<0.05 versus group 3). Blood pressure increased significantly in fructose-fed rats but fell markedly in fructose-fed rats treated with ramipril (P<0.01). Kallikrein activity measured in the heart and vessels increased as a consequence of fructose administration (P<0.05), but the administration of ramipril increased this parameter to a much greater extent (P<0.01 versus control group), which correlated closely with the decrease in blood pressure and the improvement in glucose tolerance observed in the fructose + ramipril group. CONCLUSIONS The administration of fructose as a solution in the drinking water induced glucose intolerance and increased blood pressure. Treatment with the angiotensin converting enzyme inhibitor ramipril improved glucose tolerance and significantly diminished blood pressure. Cardiovascular kinin-generating capability increased in treated animals and this increase was even higher when rats were treated with ramipril, suggesting that kinins, acting as a paracrine hormonal system, can exert cardiovascular protection and contribute to the beneficial effects of angiotensin converting enzyme inhibitor.
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Affiliation(s)
- R M Miatello
- Laboratory of Experimental Hypertension and Vasoactive Substances, School of Medicine and National Council of Research (CONICET), Mendoza, Argentina.
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Dal Ponte DB, Fogt DL, Jacob S, Henriksen EJ. Interactions of captopril and verapamil on glucose tolerance and insulin action in an animal model of insulin resistance. Metabolism 1998; 47:982-7. [PMID: 9711996 DOI: 10.1016/s0026-0495(98)90355-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have shown previously that the combination of a long-acting, non-sulfhydryl-containing angiotensin-converting enzyme (ACE) inhibitor (trandolapril) and the Ca2+ channel blocker verapamil improve insulin-stimulated glucose transport in skeletal muscle of the obese Zucker rat, a model of insulin resistance, hyperinsulinemia, and dyslipidemia. In the present study, we investigated the interactions of chronic treatment (28 days) with verapamil (20 mg/kg) and a short-acting, sulfhydryl-containing ACE inhibitor (captopril, 50 mg/kg) in combination on insulinemia, lipidemia, glucose tolerance, and insulin action on skeletal muscle glucose transport (2-deoxyglucose uptake in epitrochlearis) in lean and obese Zucker rats. In lean animals, verapamil alone and in combination with captopril actually increased (P < .05) plasma insulin, whereas in obese animals, verapamil alone worsened the hyperinsulinemia already present, and this effect was abolished by cotreatment with captopril. Captopril alone or in combination with verapamil reduced plasma free fatty acid (FFA) levels in obese rats, but not in lean rats. Captopril alone reduced the glucose-insulin index in obese animals given an oral glucose load, and this was associated with a significant increase in insulin-mediated muscle glucose transport. The greatest improvement in these responses was elicited in obese animals receiving combined captopril and verapamil treatment, and was associated with increases in muscle GLUT-4 glucose transporter protein and hexokinase and citrate synthase activities. In conclusion, these findings indicate that the short-acting, sulfhydryl-containing ACE inhibitor captopril can elicit beneficial metabolic effects on the hyperinsulinemia, dyslipidemia, glucose intolerance, and insulin resistance of muscle glucose transport of the obese Zucker rat. Moreover, there is a positive interactive effect on these pathophysiological parameters between captopril and verapamil in this animal model of insulin resistance.
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Affiliation(s)
- D B Dal Ponte
- Department of Physiology, University of Arizona College of Medicine, Tucson 85721-0093, USA
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Henriksen EJ, Jacob S, Fogt DL, Dietze GJ. Effect of chronic bradykinin administration on insulin action in an animal model of insulin resistance. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:R40-5. [PMID: 9688958 DOI: 10.1152/ajpregu.1998.275.1.r40] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The nonapeptide bradykinin (BK) has been implicated as the mediator of the beneficial effect of angiotensin-converting enzyme inhibitors on insulin-stimulated glucose transport in insulin-resistant skeletal muscle. In the present study, the effects of chronic in vivo BK treatment of obese Zucker (fa/fa) rats, a model of glucose intolerance and severe insulin resistance, on whole body glucose tolerance and skeletal muscle glucose transport activity stimulated by insulin or contractions were investigated. BK was administered subcutaneously (twice daily at 40 microg/kg body wt) for 14 consecutive days. Compared with a saline-treated obese group, the BK-treated obese animals had significantly (P < 0.05) lower fasting plasma levels of insulin (20%) and free fatty acids (26%), whereas plasma glucose was not different. During a 1 g/kg body wt oral glucose tolerance test, the glucose and insulin responses [incremental areas under the curve (AUC)] were 21 and 29% lower, respectively, in the BK-treated obese group. The glucose-insulin index, the product of the glucose and insulin AUCs and an indirect index of in vivo insulin action, was 52% lower in the BK-treated obese group compared with the obese control group. Moreover, 2-deoxyglucose uptake in the isolated epitrochlearis muscle stimulated by a maximally effective dose of insulin (2 mU/ml) was 52% greater in the BK-treated obese group. Contraction-stimulated (10 tetani) 2-deoxyglucose uptake was also enhanced by 35% as a result of the BK treatment. In conclusion, these findings indicate that in the severely insulin-resistant obese Zucker rat, chronic in vivo treatment with BK can significantly improve whole body glucose tolerance, possibly as a result of the enhanced insulin-stimulated skeletal muscle glucose transport activity observed in these animals.
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Affiliation(s)
- E J Henriksen
- Muscle Metabolism Laboratory, Department of Physiology, University of Arizona College of Medicine, Tucson, Arizona 85721-0093, USA
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12
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Erlich Y, Rosenthal T. Contribution of bradykinin to the beneficial effects of ramipril in the fructose-fed rat. J Cardiovasc Pharmacol 1998; 31:581-4. [PMID: 9554808 DOI: 10.1097/00005344-199804000-00017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The contribution of nondegraded bradykinin to the metabolic effects of the angiotensin-converting enzyme (ACE)-kininase II inhibitor ramipril was evaluated in rats rendered hypertensive, hyperinsulinemic, and hypertriglyceridemic by a fructose-enriched diet. The response of blood pressure, insulin, and triglyceride levels to concomitant administration of ramipril and the bradykinin antagonist HOE 140 was studied. Rats that received ramipril, HOE 140, or not treated at all served as controls. Treatment with ramipril reduced levels of both insulin (from 6.6 +/- 2.0 to 3.6 +/- 1.7 ng/ml; p < 0.05) and triglycerides (from 292 +/- 88 to 164 +/- 35 mg/dl; p < 0.001) as well as blood pressure (from 144 +/- 6 to 116 +/- 6 mm Hg; p < 0.001). In contrast, treatment with HOE 140 did not alter any of these parameters. The combined treatment, however, blunted the beneficial metabolic effects of ramipril on insulin (7.8 +/- 4.4 ng/ml before and 7.7 +/- 2.9 ng/ml after treatment) and triglycerides (290 +/- 135 mg/dl before and 285 +/- 152 mg/dl after treatment), whereas the hypotensive effect of ramipril was preserved (151 +/- 8 mm Hg before and 122 +/- 6 mm Hg after treatment (p < 0.001). The data suggest that whereas the hypotensive effect is mostly angiotensin-II dependent, the advantageous metabolic affect of ramipril is highly dependent on the accumulation of bradykinin.
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Affiliation(s)
- Y Erlich
- Chorley Hypertension Institute, Chaim Sheba Medical Center, Tel Hashomer, Israel
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13
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Holness MJ, Sugden MC. The impact of genetic hypertension on insulin secretion and glucoregulatory control in vivo: studies with the TGR(mRen2)27 transgenic rat. J Hypertens 1998; 16:369-76. [PMID: 9557930 DOI: 10.1097/00004872-199816030-00014] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To examine the associations among hypertension, insulin secretion, glucose tolerance and insulin resistance in vivo. DESIGN Glucose tolerance and insulin secretion during an intravenous glucose tolerance test and action of insulin on whole-body glucose kinetics in the post-absorptive state and during hyperinsulinaemia were examined in conscious, unrestrained TGR(mRen2)27 rats and age-matched transgene-negative controls. METHODS Glucose tolerance and insulin secretion were examined after intravenous administration of 500 mg glucose/kg body weight. Endogenous glucose production and whole-body glucose disposal were estimated using [3-3H]-glucose during euglycaemic-hyperinsulinaemic clamping. Muscle glucose utilization was estimated using 2-deoxy-[1-3H]-glucose. RESULTS Despite there being higher insulin levels, whole-body glucose turnover was significantly lower in post-absorptive TGR(mRen2)27 rats than it was in transgene-negative controls. This was associated with significant suppression of glucose uptake/phosphorylation by oxidative skeletal muscles. TGR(mRen2)27 rats also exhibited significantly lower blood glucose levels, higher plasma insulin levels and higher rates of disappearance of glucose after intravenous administration of glucose. During hyperinsulinaemia, steady-state glucose infusion rates required to maintain euglycaemia in TGR(mRen2)27 rats were significantly greater, indicating that an increase in whole-body action of insulin had occurred. This was due to significantly greater suppression of endogenous production of glucose: insulin-stimulated glucose disposal rates did not differ significantly between the two groups. CONCLUSIONS The results indicate that TGR(mRen2)27 rats have an enhanced and sensitized insulin-secretory response to glucose, together with a greater than normal hepatic action of insulin. Insulin-mediated glucose disposal was not impaired. The results therefore do not support the hypothesis that hypertension plays a primary role in the development of insulin resistance.
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Affiliation(s)
- M J Holness
- Department of Biochemistry, St Bartholomew's and the Royal London School of Medicine and Dentistry, London University, UK
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Young ME, Leighton B. Evidence for altered sensitivity of the nitric oxide/cGMP signalling cascade in insulin-resistant skeletal muscle. Biochem J 1998; 329 ( Pt 1):73-9. [PMID: 9405277 PMCID: PMC1219015 DOI: 10.1042/bj3290073] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nitric oxide activates guanylate cyclase to form cGMP, comprising a signalling system that is believed to be a distinct mechanism for increasing glucose transport and metabolism in skeletal muscle. The effects of a selective cGMP phosphodiesterase inhibitor, zaprinast, on basal glucose utilization was investigated in incubated rat soleus muscle preparations isolated from both insulin-sensitive (lean Zucker; Fa/?) and insulin-resistant (obese Zucker; fa/fa) rats. Zaprinast at 27 microM significantly increased cGMP levels in incubated soleus muscle isolated from lean, but not obese, Zucker rats. Muscles were incubated with 14C-labelled glucose and various concentrations of zaprinast (3, 27 and 243 microM). Zaprinast (at 27 and 243 microM) significantly increased rates of net and 14C-labelled lactate release and of glycogen synthesis in lean Zucker rat soleus muscle; glucose oxidation was also increased by 27 microM zaprinast. In addition, regardless of concentration, the phosphodiesterase inhibitor failed to increase any aspect of 14C-labelled glucose utilization in soleus muscles isolated from obese Zucker rats. The maximal activity of nitric oxide synthase (NOS) was significantly decreased in insulin-resistant obese Zucker muscles. Thus the lack of effect of zaprinast in insulin-resistant skeletal muscle is consistent with decreased NOS activity. To test whether there is a defect in insulin-resistant skeletal muscle for endogenous activation of guanylate cyclase, soleus muscles were isolated from both insulin-sensitive and insulin-resistant Zucker rats and incubated with various concentrations of the NO donor sodium nitroprusside (SNP; 0.1, 1, 5 and 15 mM). SNP significantly increased rates of net and 14C-labelled lactate release, as well as glucose oxidation in muscles isolated from both insulin-sensitive and insulin-resistant rats. A decreased response to SNP was observed in the dose-dependent generation of cGMP within isolated soleus muscles from insulin-resistant rats. A possible link between impaired NO/cGMP signalling and abnormal glucose utilization by skeletal muscle is discussed.
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Affiliation(s)
- M E Young
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K
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Klimes I, Seböková E. Hypertension and the insulin resistance syndrome of rats. Are they related? Ann N Y Acad Sci 1997; 827:13-34. [PMID: 9329739 DOI: 10.1111/j.1749-6632.1997.tb51819.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- I Klimes
- Institute of Experimental Endocrinology, Slovak Academy of Sciences, Bratislava, Slovak Republic
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Suzuki S, Ohtomo M, Satoh Y, Kawasaki H, Hirai M, Hirai A, Hirai S, Onoda M, Hinokio Y, Akai H, Toyota T. Effect of manidipine and delapril on insulin sensitivity in type 2 diabetic patients with essential hypertension. Diabetes Res Clin Pract 1996; 33:43-51. [PMID: 8877275 DOI: 10.1016/0168-8227(96)01273-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The open trial was designed to evaluate the effects of long-term antihypertensive treatment with the calcium-channel blocker, manidipine and the angiotensin converting enzyme (ACE) inhibitor, delapril on insulin sensitivity in Japanese non-insulin dependent diabetes mellitus (NIDDM) patients with essential hypertension. We measured the insulin sensitivity index (SI) and the glucose-effectiveness (SG) by the use of Bergman's minimal model method in 18 hypertensive NIDDM patients before and after administration of manidipine (group A) or delapril (group B) for 3 months. Manidipine treatment for 3 months significantly improved SI in group A from 3.35 +/- 0.61 (x 10(-4) min-1 microU-1 ml-1) to 4.70 +/- 1.34 (P < 0.05). Delapril treatment for 3 months also significantly improved SI in group B from 3.56 +/- 1.04 to 5.00 +/- 0.87 (P < 0.05). Manidipine significantly improved SG in group A from 1.60 +/- 0.64 (x 10(-2) min) to 2.19 +/- 0.38 (P < 0.05). Delapril treatment also significantly improved SG in the group B from 1.41 +/- 0.56 to 1.91 +/- 0.35 (P < 0.05). Manidipine and delapril did not affect urinary C-peptide excretion for 24 h in the hypertensive NIDDM patients. Treatment with manidipine or delapril significantly reduced systolic and diastolic blood pressures in the hypertensive NIDDM patients. There were no differences between plasma glucose, serum total triglycerides, and cholesterol or lipoprotein cholesterol fractions, heart rate and body weight after 3 months on manidipine or delapril. This study confirmed the improving effects on SI and SG by long-term treatment with manidipine or delapril in the hypertensive NIDDM patients.
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Affiliation(s)
- S Suzuki
- Third Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan
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