Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1 We have determined the dermal microvascular effects of the nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME, 100 nmol/site), endothelin-1 (ET-1, 0.1-10 pmol/site) and ET-3 (0.1-30 pmol/site) in rats with streptozotocin (STZ)-induced diabetes mellitus. Cutaneous blood flow changes as measured by a 133xenon (133Xe) clearance technique, were determined in diabetic rats four weeks after treatment with streptozotocin (STZ) and compared with responses measured in normal rats four weeks after treatment with saline. 2 Resting skin blood flow was similar in diabetic and in normal rats, as measured by 133Xe clearance and laser Doppler flowmetry. 3 Intradermal NG-nitro-L-arginine methyl ester (L-NAME) reduced skin blood flow in normal rats by 55.2 +/- 2.6% as measured by 133Xe clearance, (n = 9). L-NAME was significantly less effective in diabetic rats, inducing a 40.9 +/- 7.7% decrease in blood flow (n = 9, P less than 0.05). The enantiomer D-NAME had no effect in either group of rats. 4 Low doses of ET-1 and ET-3 injected intradermally induced dose-dependent decreases in blood flow, measured by 133Xe clearance, which were similar in both groups of rats. However, the responses to the highest doses of ET-1 (10 pmol/site) and ET-3 (10 and 30 pmol/site) were significantly reduced in the diabetic compared with the normal rats (P less than 0.05).In addition vasoconstriction to the highest doses of vasopressin (0.3 and 3 pmol/site) and vasodilatation to the neuropeptide calcitonin gene-related peptide (CGRP, 1O pmol/site) were similarly reduced in the diabetic rats (P <0.05).5. The decrease in blood flow induced by submaximal doses of ET-1 was enhanced by co-injection with L-NAME (100 nmol/site) in both diabetic and normal rats. However, this enhanced response was significantly reduced in the diabetic rats (P<0.05). A similar pattern of responses were observed to ET-3 in the presence and absence of L-NAME.6. These results indicate that the cutaneous microvasculature of rats with STZ-induced diabetes responds differently to intradermal ET-1 and ET-3 compared with normal rats; a similarly altered vascular reactivity was observed with vasopressin and CGRP. Hence, the diabetic microcirculation has impaired responses to several vasoconstrictors and a vasodilator. The effect of the nitric oxide synthase inhibitor L-NAME is also suppressed in the diabetics, suggesting that there may be decreased local production of, or response, to nitric oxide.
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PMID:Altered microvascular reactivity to endothelin-1, endothelin-3 and NG-nitro-L-arginine methyl ester in streptozotocin-induced diabetes mellitus. 139 77

Because retinal pericytes have contractile properties and are affected by diabetes, we have studied the responsiveness of pericytes to ET-1, a potent vasoconstrictor, in the presence of various concentrations of glucose. Cultured calf retinal pericytes were exposed to glucose levels of 5.5 or 25 mM for up to 8 days. Radioreceptor studies that used [125I]ET-1 showed that pericytes contained high-affinity binding sites with Kd of 3 x 10(-10) M, and these binding affinities were unaffected by glucose concentration. Receptor number appears to be elevated, but this increase was NS. Responsiveness of pericytes to ET-1 was studied with respect to stimulation of DAG and IP3 levels and PKC activities. In contrast to receptor binding, exposure to 25 mM glucose for > 6 days blunted pericyte responsiveness to ET-1. The time course of ET-1 stimulation as measured by [3H]glycerol labeling, and IP3 level showed a 98% increase in [3H]DAG at 10 min and a fourfold increase for IP3, respectively. Cells exposed to 25 mM glucose only had a 32% increase for DAG, and no increase for IP3 was observed. Dose-response studies on the stimulation of [3H]DAG increase showed the range of ET-1's effect to be between 10(-9) and 10(-7) M. At maximum, cells exposed to 5.5 mM glucose had a 70% increase versus only a 30% increase in those exposed to 25 mM glucose. Similarly, ET-1 only increased the total DAG levels in pericytes exposed to 5.5 mM glucose by 41%. PKC activity also was measured because DAG is one of its cellular activators.(ABSTRACT TRUNCATED AT 250 WORDS)
Diabetes 1992 Dec
PMID:Induction of resistance to endothelin-1's biochemical actions by elevated glucose levels in retinal pericytes. 144 93

1. This study investigated the constrictor responsiveness to endothelin-1 (ET-1, 0.1 nM-0.1 microM) of aortic rings (under 10 g resting tension in Krebs solution) from 2- and 6-week streptozotocin (STZ, 60 mg kg-1, i.v.)-induced diabetic rats and vehicle-treated control rats. 2. In aortae from 2- and 6-week STZ-treated rats, and their corresponding controls, removal of endothelium caused leftward shifts of ET-1 concentration-response curves without affecting maximum responses. 3. Maximum responses to ET-1 were reduced in aortae from both 2- and 6-week STZ-treated rats compared to those from control rats. Such reductions were still evident after removal of the endothelium. 4. Decreased responsiveness to ET-1 of aortae from 2-week STZ-treated rats was still evident after chronic treatment with the aldose reductase inhibitor epalrestat, but not after chronic insulin treatment or in aortae bathed in high glucose (30 mM) Krebs solution. 5. Decreased responsiveness to ET-1 of aortae from 6-week STZ-treated rats (compared with those from controls) was still evident after chronic epalrestat treatment and in high glucose Krebs solution. 6. These data suggest that the decreased responsiveness to ET-1 observed in aortae from 2- and 6-week STZ-induced diabetic rats is not due to abnormal activity of the polyol pathway. The altered responsiveness in aortae from 2-week diabetic rats (compared with those from control rats) may possibly be a manifestation of changes (adaptive or otherwise) which occur as a result of high glucose concentrations in vivo.However, in aortae from rats with diabetes of longer duration, other mechanisms may also play a role in the altered responsiveness, since it was no longer reversible by bathing in high glucose Krebs solution.
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PMID:Effects of glucose, insulin or aldose reductase inhibition on responses to endothelin-1 of aortic rings from streptozotocin-induced diabetic rats. 150 47

In order to gain insight into the potential role of endothelin, a 21 amino acid peptide produced by endothelial cells, in the development of complications of diabetes mellitus, basal plasma endothelin levels were measured in 152 patients with diabetes mellitus (83 patients with type 1 diabetes mellitus, 69 patients with type 2 diabetes mellitus) and compared to those in 50 healthy controls. Blood was drawn at 8:00 AM under resting conditions and endothelin was measured after prior extraction by a sensitive radioimmunoassay specific for both endothelin 1 and 2. Endothelin levels were increased in patients with diabetes mellitus in comparison to controls. In type 1 diabetes mellitus a positive correlation between endothelin levels and age was found. We found that 60% of patients with type 1 diabetes mellitus and elevated endothelin levels higher than 2.5 pg/mL (highest value in a control person) had had diabetes for more than 20 years (P less than .05 v patients with normal endothelin levels). In type 2 diabetes mellitus the relation between elevated endothelin levels and diabetes duration was reversed. Glycosylated hemoglobin (HbA1) concentrations above 10% of total hemoglobin were measured in 62% of the patients. Arterial hypertension was present in 60% of the patients with type 1 diabetes mellitus and increased endothelin levels greater than 2.5 pg/mL (both P less than .05 v patients with normal endothelin levels).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Increased plasma levels of endothelin in diabetic patients with hypertension. 157 42

Immunoreactive (ir)-endothelin (ET) in urine was studied with a radioimmunoassay in patients with diabetes mellitus (DM) and non-DM diseases including endocrine disorders, primary glomerular diseases, autoimmune diseases, and hematological malignancies. Twenty-four-hour excretions (mean +/- SEM) of ir-ET were 8.0 +/- 0.9 pmol/day in the DM group (n = 13) and 9.5 +/- 1.2 pmol/day in the non-DM group (n = 51). No significant differences among DM and other disease groups were noted with respect to 24-h ir-ET excretion. Reverse-phase high-performance liquid chromatography of a normal urine extract revealed a major peak eluting later than ET-1. Gel chromatography revealed a single major peak in a smaller molecular weight (MW) region in normal urine and an additional peak in larger MW region in a urine extract from a DM patient. Urinary ir-ET consists of at least two components which may be metabolites of ET or ET precursors in plasma or peptides derived from the kidney.
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PMID:Immunoreactive endothelin in urine of patients with and without diabetes mellitus. 172 99

The vasoconstrictor response is defective in diabetes mellitus (DM). Activation of protein kinase C (PKC) is also known to prevail in diabetes mellitus, and it is thought to be secondary to abnormal diacylglycerol metabolism. To ascertain whether this PKC activation in diabetes underlies the vasomotor defect by regulating biological receptors, we studied the characteristics of the receptor for endothelin (ET), "the vasoconstrictor of injury." For this purpose, diabetes was induced in rats by intravenous streptozotocin. One to 2 weeks after streptozotocin treatment (average glucose at time of experiments: 518 mg/dl), glomeruli were isolated and assessed for ET receptor and PKC activity. ET receptor characteristics were also assessed following infusion of a specific PKC inhibitor, 1-(5-isoquinolinesulfonyl)piperazine (CI). For comparison, nondiabetic controls with and without PKC inhibitor were studied. No differences in high-affinity ET-1 receptor (ER-1) characteristics were found among the diabetic and normal rats. In contrast, receptor density for the lower-affinity receptor (ER-2) was significantly depressed in DM without changes in the equilibrium dissociation constant. Infusion of CI 20 min before glomerular harvesting did not affect the glomerular PKC activity in controls (particulate: 28.0 +/- 4.0% of total activity to 22.0 +/- 3.9%, n = 3). In contrast, in diabetes mellitus rats infused with CI, PKC activity decreased (particulate: from 44.7 +/- 2.9% of total activity to 18.5 +/- 3.2%, n = 3, p less than 0.05). This CI-induced suppression of PKC in DM was accompanied by complete reversal in down-regulation of ER-2 receptors. Thus, DM is characterized by down-regulation in low-affinity ET-1 receptors. Furthermore, this receptor down-regulation can be reversed by abolishing abnormally enhanced PKC activity. These results indicate that abnormal activation of PKC may underlie the profoundly vasodilative status and defective vasoconstrictor response characterizing DM.
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PMID:Down-regulation of endothelin-1 receptors by protein kinase C in streptozotocin diabetic rats. 172 24

1. This study investigated the responsiveness to vasoconstrictor agents (including endothelin-1, ET-1) of aortic rings from rats with two-week streptozotocin (STZ, 60 mg kg-1, i.v.)-induced diabetes and vehicle-treated control rats. The basal tension was 10 g, which was estimated to be more physiological than the tension of 1-2 g that has been previously used for most studies of aortic rings from diabetic rats. 2. Maximum responses to ET-1 (0.13-18 nM), KCl (2-20 mM) or CaCl2 (10 microM-10 mM) were reduced in aortae from STZ-treated rats compared to those from control rats. Such reductions were still evident after removal of the endothelium. 3. Responses to noradrenaline (NA, 0.1 nM-26 microM) of aortae from STZ-treated rats were not significantly different from responses of aortae of control rats. 4. Removal of endothelium resulted in a significant reduction in the EC50 values for NA of rings from both STZ-treated rats (6.90 +/- 0.13 and 8.17 +/- 0.35 (-log M) with and without endothelium, respectively, n = 5) and control rats (6.90 +/- 0.15 and 8.37 +/- 0.44 (-log M) with and without endothelium, respectively, n = 5). 5. In calcium-free medium (with 1 mM EGTA), responses to NA and ET-1 were reduced compared with those in normal Krebs solution and maximum responses were less in rings from STZ-treated compared with control rats. 6. Indomethacin (5 microM) did not prevent the reduced maximum responsiveness to ET-1 in rings from STZ-treated rats compared with those from controls.7. This study indicates that changes in vascular responsiveness to ET-1, KCI and CaCl2 (but not NA) occur in aortae of two-week STZ-treated rats. The endothelium does not appear to play a major role in mediating changes in responsiveness to ET-1.
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PMID:Attenuated responses to endothelin-1, KCl and CaCl2, but not noradrenaline, of aortae from rats with streptozotocin-induced diabetes mellitus. 181 Jun 3

We measured the release of immunoreactive endothelin-1 (IR-ET-1) by cultured porcine aortic endothelial cells under normoglycemic (5.5 mmol/L) and hyperglycemic (27.5 and 55 mmol/L) conditions. Compared with cells incubated in the presence of a normal glucose concentration, cells incubated in 27.5 mmol/L glucose medium released 52% less IR-ET-1, and those incubated in 55 mmol/L glucose medium released 54% less IR-ET-1. The observed effects of elevated glucose on IR-ET-1 release were both sugar-specific and not due to increased osmolarity. Fetal calf serum (FCS)-stimulated IR-ET-1 release in the presence of elevated glucose was also less than that in the presence of a normal glucose concentration. In addition, the effects of two hormones, insulin and insulin-like growth factor 1 (IGF-1), on IR-ET-1 release were examined. Both insulin and IGF-1 dose-dependently stimulated IR-ET-1 release. Twenty micrograms/mL insulin and 10(-8) mol/L IGF-1 increased IR-ET-1 release by 38% and by 44%, respectively. These results indicate that hyperglycemic condition results in reduction of IR-ET-1 release from cultured porcine aortic endothelial cells and that insulin and IGF-1 stimulate its release. The possible relevance of these observations to physiological regulation of ET-1 release in vivo and pathological processes in diabetes remains to be established.
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PMID:Effect of glucose and insulin on immunoreactive endothelin-1 release from cultured porcine aortic endothelial cells. 198 73

Endothelinlike immunoreactivity was detected by radioimmunoassay in medium conditioned by cultured endothelial cells obtained from bovine retinal microvessels (9.2 +/- 6.5 pM, n = 4). Sephadex G-25 column chromatography and fast-protein liquid chromatography revealed that most of the endothelinlike immunoreactivity was eluted in an identical position to synthetic endothelin 1. Retinal capillary pericyte-conditioned medium contained 2.9 pM endothelinlike immunoreactivity. In contrast to endothelial cells, retinal pericytes were found to bind endothelin. The dissociation constant and binding capacity were 0.14 nM and 1.5 x 10(5) sites/cell (n = 3), respectively. These findings suggest that endothelin produced by the retinal endothelial cells binds to the pericytes, adding support to the suggestion that pericytes in the retina may have a musclelike function.
Diabetes 1989 Sep
PMID:Production of endothelin 1 by cultured bovine retinal endothelial cells and presence of endothelin receptors on associated pericytes. 254 10

Retinal capillary pericyte is a cell type selectively lost in early diabetic retinopathy. The physiological function of pericytes is not yet clearly identified, although it probably has contractile properties. We determined the specific binding of endothelin 1, a 21-amino acid peptide with potent vasoconstrictive action, and the stimulation of diacylglycerol/protein kinase C (DAG/PKC) pathway in cultured retinal capillary pericytes by endothelin. A single specific binding site for 125I-labeled endothelin was identified, with an apparent Kd of 1.3 nM and a maximal binding capacity of approximately 1-2 x 10(5) sites/cell. Endothelin (100 nM) increased total cellular DAG content by 15% at 5 min and 24% at 10 min. When pericytes were labeled isotopically with [3H]glycerol, endothelin stimulated [3H]DAG formation by 100% at 10 min and 88% at 30 min. After 10 min of endothelin treatment, PKC activities were increased by 60 and 100% in the membranous and cytosolic pools, respectively. We conclude that bovine retinal capillary pericytes possess numerous high-affinity specific binding sites for endothelin that mediate the action of endothelin by the stimulation of the DAG/PKC pathway in pericytes. These findings suggest that endothelin is a regulator of the contractile properties of pericytes, which may be adversely affected in diabetic retinopathy.
Diabetes 1989 Dec
PMID:Characterization of endothelin receptors and effects of endothelin on diacylglycerol and protein kinase C in retinal capillary pericytes. 839 Feb 75


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