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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effect of administration of the angiotensin converting enzyme inhibitor (ACEI), lisinopril (Carace; 10-40 mg twice daily) and the calcium channel blocker, nifedipine (Adalat Retard; 20-40 mg twice daily) on ex vivo [45Ca2+] uptake by platelets from hypertensive diabetic (type 1 and 2) patients was investigated. 2. At the end of at least 3 months treatment, blood was collected prior to the patient taking the morning dose of medication and washed platelets prepared. [45Ca2+] uptake was monitored following the addition of adrenaline, isoprenaline and dibutyryl cAMP (dbcAMP), as well as in unstimulated (zero) platelets. 3. Both nifedipine and lisinopril significantly inhibited the ex vivo uptake of [45Ca2+] by platelets when this process was stimulated by adrenaline, isoprenaline and dibutyryl cAMP. Basal uptake was also inhibited in both groups. 4. These data consolidate the hypothesis that ACE inhibitors may possess calcium channel/calcium mobilisation blocking properties. Apart from its hypertensive action, lisinopril may also reduce platelet activity via modulation of calcium dynamics, thereby reducing the incidence of vascular complications associated with diabetes mellitus.
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PMID:Lisinopril and nifedipine administration inhibits the ex vivo uptake of [45Ca2+] by platelets from hypertensive diabetic patients. 131 54

The status of Ca(2+)-channels and adrenoceptors in the hind leg skeletal muscle was examined in rats 8 weeks after inducing diabetes by an intravenous injection of streptozotocin (65 mg/kg). Scatchard plot analysis of the data on specific binding of 3H-nitrendipine with crude membranes from diabetic muscle revealed an increase in the density of Ca(2+)-channels without any significant change in their affinity for the ligand. An increase in the density of beta-adrenoceptors without any alteration in their affinity, as measured by 3H-dihydroalprenolol binding, was also evident in the diabetic muscle. The observed increase in the number of Ca2+ channels or beta-adrenoceptors seems specific since no change in the alpha-adrenoceptor density or affinity, as measured by 3H-prazosin binding, was seen in the diabetic membranes. These results support the view that higher activities of Ca2+ transport systems or regulatory mechanisms may be associated with hyperfunction of the diabetic skeletal muscle.
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PMID:Ca(2+)-channels and adrenoceptors in diabetic skeletal muscle. 131 90

Functional changes in the urinary bladder obtained from diabetic rats were investigated by determining the responsiveness to acetylcholine (ACh). Maximal contraction of the detrusor strips in response to ACh was significantly enhanced in the diabetic rats. Ca(2+)-induced contracture of the detrusor strips, which had been incubated with 10(-3) M ACh in the presence of nicardipine in Ca(2+)-free medium, was significantly augmented in diabetic rats. Ca(2+)-contracture in Ca(2+)-free, isotonic high-K+ (60 mM) medium was not changed in diabetic state. The density of muscarinic receptors to 3H-QNB was significantly higher in the bladder from diabetic rats compared to age-matched control rats. These results suggest that tone of the autonomic nervous system in the bladder may be decreased in diabetes and, thus, compensatory increase in density of muscarinic receptors may occur. Furthermore, an increased contractile response of the detrusor strips of the urinary bladder to ACh in diabetic rats also may be due to an increased influx of extracellular Ca2+ through the receptor-operated Ca2+ channels but not the voltage-dependent Ca2+ channels.
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PMID:Changes in muscarinic responsiveness, muscarinic receptor density and Ca2+ mobilization of the urinary bladder in streptozotocin-induced diabetic rats. 131 64

To determine the relations of diet with risk of clinical noninsulin-dependent diabetes, we analyzed data from a prospective cohort of 84360 US women. During 6 y of follow-up we identified 702 definite incident cases. Because body mass index (BMI) is a powerful risk factor for diabetes, we examined the relations of fat (including type), fiber, sucrose, and other components of diet to risk of diabetes, among women with BMIs (in kg/m2) less than 29 kg/m2. After controlling for body mass index, previous weight change, and alcohol intake, we observed no associations between intakes of energy, protein, sucrose, carbohydrate, or fiber and risk of diabetes. Compared with women in the lowest quintile of energy-adjusted intake, and relative risks (and tests for trend) for those in the highest quintile were 0.61 (P trend = 0.03) for vegetable fat, 0.62 (P trend = 0.008) for potassium, 0.70 (P trend = 0.005) for calcium, and 0.68 (P trend = 0.02) for magnesium. These inverse associations were attenuated among obese women (BMIs greater than or equal to 29).
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PMID:Diet and risk of clinical diabetes in women. 131 20

Transient exposure of rat pancreatic B-cell to 50 mM K+ ([K+50]) makes exocytosis unresponsive to further depolarization, i.e., stimulation with 100 mM K+ or 1 uM glyburide, which closes the ATP-sensitive K+ (K+ATP) channel, simultaneously with [K+50] does not produce any greater insulin secretion compared with [K+50] alone. In sharp contrast, 16.7 mM glucose ([G16.7]) applied simultaneously with [K+50] elicits an insulin response markedly greater than that produced by [K+50] alone, which is not attenuated by 100 uM diazoxide, an inhibitor of K+ATP channel closure. [G16.7]-induced insulin secretion at the basal K+ concn of 4.7 mM was greatly (93%) suppressed by 100 uM diazoxide. Insulin secretion induced by [K+50] plus [G16.7] ([K+50 + G16.7]) was markedly suppressed (70%) by 1 uM nifedipine, a Ca(2+)-channel blocker and was completely abolished by 2 mM 2-cyclohexen-1-one, which reportedly decreases reduced glutathione level and blocks glucokinase. This finding indicates that insulin release induced by [K+50 + G16.7] is not due to leakage produced by toxic stimuli but to activation of exocytosis. When graded concentrations (25 and 50 mM) of K+ were applied simultaneously with [G16.7] in the presence of 100 uM diazoxide, insulin response was clearly dependent on K+ concentration, indicating that the physiological range of membrane depolarization also activates the glucose-responsive effector. Membrane depolarization/Ca2+ influx directly stimulates hormone exocytosis on one hand and activates the K+ATP channel-independent glucose-responsive effector or effectors on the other in the B-cell. The nature of the glucose-responsive effector or effectors remains to be established.
Diabetes 1992 Apr
PMID:Dual functional role of membrane depolarization/Ca2+ influx in rat pancreatic B-cell. 131 55

In order to examine the status of Ca2+ channels in heart sarcolemma during the development of diabetes, rats were injected intravenously with 65 mg/kg streptozotocin and hearts were removed 1, 3 and 8 weeks later. Crude membranes from the ventricular muscle were prepared and the specific binding of 3H-nitrendipine was studied by employing different concentrations of this Ca(2+)-antagonist. A significant decrease in both dissociation constant and maximal number of 3H-nitrendipine binding was observed in 3 and 8 weeks diabetic preparations. No such alterations were evident in diabetic brain membranes. Treatment of diabetic animals with insulin prevented the occurrence of these changes in the myocardium. The altered 3H-nitrendipine binding characteristics in diabetic heart membranes may not be due to the high levels of circulating catecholamines in this experimental model because no such changes were seen upon injecting a high dose (40 mg/kg) of isoproterenol in rats for 24 hr. The reduced number of 3H-nitrendipine binding sites may decrease Ca(2+)-influx through voltage sensitive Ca2+ channels and partly explain the depressed cardiac contractile force development in chronic diabetes whereas the increased affinity of Ca2+ channels may partly explain the increased sensitivity of diabetic heart to Ca2+.
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PMID:Alterations in Ca(2+)-channels during the development of diabetic cardiomyopathy. 132 Jul 33

This study was undertaken to test the hypothesis that, given equal arterial pressure reductions, the combination of an angiotensin converting enzyme (ACE) inhibitor and calcium antagonist slows declines in renal function and yields greater reductions in albuminuria over either agent alone. This hypothesis was evaluated in four groups of hypertensive, non-insulin dependent, diabetic subjects with renal insufficiency (N = 30). Renal hemodynamics, albuminuria and metabolic parameters were evaluated for a period of one year. Subjects were all placed on a 90 mEq sodium, 0.8 g/kg protein, 1500 calorie American Diabetes Association diet for the entire length of the study. Subjects were followed for two weeks off antihypertensive medications and were subsequently randomized to either lisinopril, alone (group I), sustained release verapamil, alone (group II), reduced doses of both lisinopril and sustained release verapamil (group III), and hydrochlorothiazide with guanfacine (group IV). At the end of one year group III had the greatest reduction in albuminuria (78 +/- 7%, group III vs. 59% +/- 4, group I: P less than 0.05). In addition, the decline in glomerular filtration rate (GFR) was the lowest in this group (0.28 +/- 0.07, group III vs. 0.69 +/- 0.12, group I; P less than 0.05) although there was no significant difference between groups II and IV. The highest side effect profiles were noted in group IV, the least in group III. The greatest reductions in renal hemodynamics occurred in all groups within the first month; however, striking differences between groups were noted (7.4 +/- 2%, group I vs. 1.4 +/- 2%, group III; P less than 0.05). We conclude that the combination of reduced doses of an ACE inhibitor and calcium antagonist attenuate both albuminuria and the rate of decline in glomerular filtration rate. Furthermore, the combination of these classes of agents appear to yield the lowest side effect profile over either agent alone. Lastly, high doses of ACE inhibition alone may be detrimental to renal function in late stage diabetics with renal insufficiency.
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PMID:Treatment of arterial hypertension in diabetic humans: importance of therapeutic selection. 132 10

We investigated whether biologically relevant concentrations of the mono-hydroxyeicosatetraenoic acids (mono-HETEs) modulate platelet functions. We report that 15-HETE, an eicosanoid produced by endothelial cells, granulocytes, and lymphocytes, potentiated platelet aggregation, nucleotide release, and elevation in intracellular calcium levels induced by a threshold concentration of thrombin (0.025 U/mL). Significant potentiation effects on these responses were observed at concentrations between 1 and 100 nmol/L. 15-HETE at these concentrations enhanced thrombin-induced platelet aggregation by 32% to 57%, nucleotide release by 40% to 65%, and elevation of intracellular calcium by 31% to 52% (P < .05 to .01). Both 12-HETE and 5-HETE, the structural isomers of 15-HETE, also potentiated thrombin-induced platelet aggregation and nucleotide release. While 12-HETE showed a small but significant effect at 100 pmol/L, 5-HETE had effects similar to those of 15-HETE at micromolar concentrations. To understand the mechanism of the HETE modulation of platelet functions, we studied the effect of 10 and 100 nmol/L 15-HETE on the production of sn-1,2-diacylglycerol (DAG) and inositol-1,4,5-trisphosphate (1,4,5-IP3). 15-HETE enhanced thrombin-induced production of DAG and 1,4,5-IP3 in a time- and concentration-dependent manner. 15-HETE also potentiated agonist-induced phosphorylation of the 47-Kd platelet protein. These studies demonstrate an important modulatory role for 15-HETE on platelet functions. Since this eicosanoid is elevated in pathologic states associated with platelet hyperfunction, including diabetes mellitus and atherosclerosis, an elucidation of its mechanism(s) of action appears relevant to our understanding of the genesis of atherothrombotic vascular disease.
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PMID:15-Hydroxyeicosatetraenoic acid-mediated potentiation of thrombin-induced platelet functions occurs via enhanced production of phosphoinositide-derived second messengers--sn-1,2-diacylglycerol and inositol-1,4,5-trisphosphate. 133 1

Blood flow autoregulation is impaired in early diabetes mellitus, predisposing the microvasculature to injury. Blood flow autoregulation is in part a myogenic response that is critically dependent on Ca2+ uptake via voltage-sensitive calcium channels in vascular smooth muscle cells (VSMC). Recent evidence suggests that impairment of blood flow autoregulation in diabetes may be responsive to variations in glycemic control. The present study thus examined the independent effect of an elevated extracellular glucose concentration on Ca2+ uptake by cultured rat VSMC in vitro. A threshold glucose concentration of 15-20 mmol/l markedly and maximally depressed basal and voltage sensitive Ca2+ channel activated (BAY K 8644, 10(-7) M) Ca2+ uptake. This effect was apparent within 3 h of incubating VSMC with the high glucose medium and was maximal after 48 h incubation. Osmotic control media containing either mannitol or L-glucose did not inhibit Ca2+ uptake by VSMC, thus confirming the effect was specific for elevated extracellular glucose concentrations and unrelated to changes in extracellular osmolality. Glucose-induced inhibition of basal and voltage-sensitive transmembrane fluxes of Ca2+ in VSMC may provide a metabolic mechanism for impaired calcium-dependent blood flow autoregulatory responses in early diabetes mellitus.
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PMID:Effect of elevated extracellular glucose concentrations on calcium ion uptake by cultured rat vascular smooth muscle cells. 133 25

Although inhibition of Na(+)-K+ ATPase has been described in the diabetic heart, K+ loss from myocardium has not been observed in a canine model of mild diabetes. The finding of tissue Na+ accumulation and a potential relation to alteration of left ventricular inositol as observed in other tissues in diabetes form the basis of this investigation. Diabetes was induced with alloxan in three groups of male mongrel dogs who were studied after 1 yr. In the initial experiment the tissue compartment volumes, determined with intravenous 51Cr EDTA as a marker, were found to be normal. Calculated cell sodium was increased to 32.8 +/- 2.6 mEq/kg cell H2O vs 18.7 +/- 1.1 in controls (p < 0.01). Cell potassium in diabetes was normal. In the second group, myocardial polyols were analyzed by gas-liquid chromatography. Inositol was diminished in diabetes to 0.61 +/- 23 microM/g of left ventricle, vs the respective control levels of 1.9 +/- 0.57 microM/g (p < 0.02). Sorbitol concentration was unaltered. Left ventricular sodium increments were not associated with altered tissue calcium. In group III the hypothesis that inhibition of Na(+)-K+ ATPase in diabetes might not elicit the expected alteration of K+ transport was assessed during intracoronary infusion of acetyl strophanthidin. No difference in cation responses from control was observed. It is postulated that a change in the conformation of Na(+)-K+ ATPase, with high affinity sodium binding sites facing the intracellular compartment, may render sodium less releasable from cell membrane.
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PMID:Myocardial inositol and sodium in diabetes. 133 48


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