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

The effects of combined renovascular hypertension and diabetes mellitus on the rat heart were investigated in order to detect possible synergistic effects of the two conditions. Hypertensive diabetic and hypertensive nondiabetic young male Wistar rats were compared with diabetic and non-diabetic controls. Since the normal body weight increase of the diabetic animals was markedly suppressed a weight-matched nondiabetic control group was introduced in addition. Hypertension was established for eight weeks by a surgical stenosis of the left renal artery, diabetes mellitus was maintained for four weeks after a single intraperitoneal injection of 75 mg/kg streptozotocin. Light and electron microscopic stereological parameters were obtained for the left ventricular papillary muscles. The whole hearts were also investigated histologically. Qualitative morphology failed to substantiate synergistic effects in the hypertensive diabetic rats. Vascular abnormalities were not observed. The stereological parameters, however, revealed microstructural reactions which were observed exclusively in the hypertensive diabetic group: the volume ratio of mitochondria-to-myofibrils was decreased, the surface-to-volume ratio of mitochondria was increased (reduction of mitochondrial size) and the mean cross sectional area of capillaries was decreased. Similar quantitative mitochondrial changes have been frequently described in long-standing hypertension, but in the present investigation, they were not found in the nondiabetic hypertensive group. It is therefore concluded that diabetes mellitus potentiates the effects of chronic pressure overload on myocardial cells. However, the myocardial fibrosis which has been found by other groups at later stages of hypertension and/or diabetes mellitus was not detected in the present study. The reduced mean cross sectional area of capillaries in hypertensive-diabetic rats may be correlated with early molecular changes of the myocardial interstitium or with early abnormalities of small arteries. Thus our stereological results support the hypothesis that a non-coronary hypertensive diabetic cardiomyopathy occurs in mammalian hearts.
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PMID:Synergistic effects of diabetes mellitus and renovascular hypertension on the rat heart--stereological investigations on papillary muscles. 296 73

Biochemical and myocardial functional changes were determined in rabbits made diabetic with alloxan (100 mg/kg, intravenously, two injections 24 h apart). Alloxan-induced diabetes was characterized by a state of hypoinsulinaemia and hyperglycaemia. After 10 weeks of diabetes, significant decreases in heart and left ventricular weights as well as increased serum and heart triglycerides and cholesterol were observed in the diabetic animals (p less than 0.05). In addition, left ventricular pressure, heart rate and rate of left ventricular pressure development were all decreased in the animals. The diabetic state was also associated with a slight elevation in myocardial calcium and a significant decrease in magnesium levels (p less than 0.05). Subcellular fractionation of diabetic hearts indicated the presence of alterations in myofibrillar and sarcoplasmic reticulum marker enzymes (p less than 0.05). Among the lysosomal enzymes, measured, N-acetyl-beta-glucosaminidase activity was significantly increased in the homogenates of diabetic left ventricles (p less than 0.05). These alterations in hearts of diabetic rabbits may be responsible for some aspects of diabetic cardiomyopathy.
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PMID:Biochemical and functional changes in hearts from rabbits with diabetes. 299 85

The structural effects of diabetes and subsequent insulin treatment upon the contractile and supporting elements of the rat myocardium were examined at progressive stages of both untreated and treated disease. Diabetes was induced by intravenous injection of alloxan, and tissue was examined after 6, 12, and 26 weeks. Insulin treatment began after 12 weeks of diabetes and tissue from these animals was examined after the same intervals. Within the cardiocytes, diabetes produced a focal yet progressive loss of myofibrils, transverse tubules, and sarcoplasmic reticulum, and separation of the fasciae adherens was evident at the intercalated disk. Mitochondrial damage was not evident. These cytoplasmic alterations were accompanied by intercellular and perivascular deposition of connective tissue, thickening of the endothelial cytoplasm with pinocytotic hyperactivity, and characteristic basal laminar changes. When insulin treatment began after 12 weeks of diabetes, most, but not all, of these changes were reversed, and this reversal was essentially complete within 6-12 weeks. Even with longer periods of insulin treatment, cardiocytes still exhibited scattered areas of myofibril loss and extracellular matrix was retained. In contrast, diabetic changes in the intercalated disk and capillaries, including their basal laminae, were completely and rapidly reversed. It is hypothesized that the structural manifestations of diabetic cardiomyopathy consist of two major components; the first is a short-term, physiologic adaptation to metabolic alterations, while the other represents degenerative changes for which the myocardium has only a limited capacity for repair.
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PMID:Structural manifestations of diabetic cardiomyopathy in the rat and its reversal by insulin treatment. 306 14

The presence of diabetic cardiomyopathy and its relationship to concurrent hormonal and metabolic status have not been defined in patients with uncomplicated type I diabetes mellitus. Accordingly, radionuclide left ventricular angiograms and simultaneous metabolic profiles were obtained in 8 type I diabetic patients who had no major diabetic complications and in 11 normal subjects. Occult coronary artery disease was excluded by electrocardiogram exercise testing. Hemodynamics and systolic function did not differ between the groups. However, the peak filling rate (PFR; end-diastolic volumes per s) was less in the diabetic patients at rest [mean, 4.1 +/- 0.2 (+/- SE) vs. 4.8 +/- 0.2; P less than 0.05] and during aerobic (6.8 +/- 0.2 vs. 8.30 +/- 0.3; P less than 0.01) and anaerobic exercise (8.8 +/- 0.3 vs. 9.8 +/- 0.4; P less than 0.05). The time to PFR was prolonged in the diabetic patients at rest (174 +/- 10 vs. 133 +/- 7 ms; P less than 0.01) and during anaerobic exercise (126 +/- 5 vs. 103 +/- 6 ms; P less than 0.01). Plasma glucose and insulin levels were elevated in the diabetic patients at rest and during exercise. Otherwise, the metabolic and hormonal levels did not differ between the groups. In the diabetic patients, no single metabolic or hormonal parameter correlated with PFR or time to PFR. Impairment of diastolic filling also did not correlate with level of glycosylated hemoglobin or duration of diabetes. The alteration in diastolic filling present in type I diabetic patients who have no other diabetic complications may represent the earliest functional effect of diabetic cardiomyopathy.
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PMID:The relationship of cardiac diastolic dysfunction to concurrent hormonal and metabolic status in type I diabetes mellitus. 327 82

The ability of hearts to store, distribute, and release norepinephrine (NE) was investigated in rats 8 wk after the induction of diabetes by an injection of streptozotocin (65 mg/kg iv). Chronic diabetes was associated with increased content and concentration of NE in heart and in other tissues such as kidney, brain, and spleen. Reserpine or tyramine treatment resulted in depletion of endogenous cardiac NE in control and diabetic rats. The depletion of NE stores at different times after a dose of reserpine was greater in diabetic hearts. On the other hand, NE stores in diabetic hearts were less sensitive than control hearts to low doses of tyramine but were more sensitive to high doses. The uptake of [3H]NE was greater in diabetic hearts in isolated perfused preparations. In comparison with the control values, diabetic hearts showed a decrease in [3H]NE in the granular fraction and an increase in the supernatant fraction. Diabetic hearts also showed an accelerated spontaneous release of [3H]NE. The increased cardiac NE and the uptake and release of NE in diabetic animals were reversible upon treatment with insulin. These results are consistent with the view that sympathetic activity is increased in diabetic cardiomyopathy and indicate that cardiac NE in diabetic rats is maintained at a higher level partly due to an increased uptake of released NE by adrenergic nerve terminals.
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PMID:Norepinephrine storage, distribution, and release in diabetic cardiomyopathy. 329 80

Quantitative electrocardiographic (ECG) and vectorcardiographic (VCG) analysis was carried out in 113 newly diagnosed, middle-aged, non-insulin-dependent diabetics (61 men, 52 women) and 125 non-diabetic control subjects (56 men, 69 women) in order to explore changes attributable to non-coronary heart disease (diabetic cardiomyopathy) in diabetics. Diabetic men had a prolonged PQ interval and women a more negative P-terminal force and a more leftward frontal QRS axis than their non-diabetic counterparts, but no other significant differences we found between diabetic and non-diabetic subjects in various quantitative ECG and VCG variables when the effect of confounding factors (age, obesity, coronary heart disease, hypertension, drugs) was taken into account. The more negative P-terminal force and left axis deviation in diabetic women could be explained by a concomitant left ventricular hypertrophy among them. Non-insulin-dependent (type 2) diabetes, which is commonly preceded by a long duration of asymptomatic hyperglycaemia, is not associated, early in its clinical course, with major ECG and VCG abnormalities suggestive of diabetic cardiomyopathy.
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PMID:Quantitative electrocardiographic and vectorcardiographic study on newly-diagnosed non-insulin-dependent diabetic and non-diabetic control subjects. 334 19

It has been suggested that the occurrence of an intracellular Ca2+ overload may result in the development of diabetic cardiomyopathy, which is associated with depletion of high-energy phosphate stores and a derangement of ultrastructure and cardiac dysfunction. Accordingly, the effects of verapamil, a Ca2+ antagonist, on cardiac function, ultrastructure, and high-energy phosphate stores in the myocardium were evaluated in rats made diabetic by an intravenous injection of streptozocin (65 mg/kg). Four weeks after the induction of diabetes, the animals were treated with three doses (2, 4, or 8 mg.kg-1.day-1) of verapamil for 4 wk until they were used for the measurement of different parameters. Untreated diabetic animals had slower heart rates, depressed rate of contraction and rate of relaxation, lower peak left ventricular systolic pressure, and elevated left ventricular diastolic pressure. All of these changes were significantly improved in diabetic rats receiving verapamil treatment. The beneficial effects of verapamil were more evident with higher doses (8 mg.kg-1.day-1) than with the lower doses (2 mg.kg-1.day-1). The diabetic animals also showed alterations in myocardial high-energy phosphate stores and exhibited evidence of ultrastructural damage; these abnormalities were improved by verapamil treatment without affecting their hyperglycemic status. Our results demonstrate that verapamil is capable of preventing diabetes-induced myocardial changes and support the involvement of Ca2+ in the cardiac pathology during diabetes.
Diabetes 1988 Jul
PMID:Beneficial effects of verapamil in diabetic cardiomyopathy. 338 88

The effects of chronic experimental diabetes on electrophysiological properties, contractile behavior, 45Ca2+ transport, fatty acid profiles and ultrastructural characteristics were studied in enzymatically dissociated ventricular myocytes. Diabetes was induced in rats by streptozotocin administration and animals were killed 8-10 weeks later. Myocytes from diabetic rats exhibited electrical behavior similar to that of myocytes from control rats, but their contractile properties were altered. Their sensitivity of the twitch contractions to various positive and negative inotropic agents (isoproterenol, norepinephrine, phenylephrine, acetylcholine, ouabain and veratridine) was greatly diminished. However, a part of the contractile response (the tonic, sustained contractions) were increased in the diabetic myocytes, indicating that the changes are not caused by a decreased sensitivity of myofilaments. Furthermore, the diabetic myocytes exhibited also significant decrease in total Ca2+ content. The fatty acid profile in the diabetic group was changed mainly in that there were slightly elevated levels of docosahexaenoic acid and diminished levels of palmitic acid. The ultrastructure of the diabetic myocytes was affected only slightly. These investigations offer for the first time a comprehensive picture of changes related to diabetic cardiomyopathy as they occur at the level of cardiomyocytes.
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PMID:Effects of chronic diabetes mellitus on the electrical and contractile activities, 45Ca2+ transport, fatty acid profiles and ultrastructure of isolated rat ventricular myocytes. 338 90

To assess the adaptation of the heart of diabetic subjects in the natural volume overload state of pregnancy, echocardiography was performed during each trimester and postpartum in 17 women with insulin-dependent diabetes mellitus (IDDM) and in 11 healthy women. The mean duration of diabetes was 14 yr and signs of microvascular complications were detected in 6 patients. The diabetic women had slightly smaller left ventricles than the control women already in the basal state (postpartum), and the pregnancy-induced increase in left ventricular size and stroke volume was less in the diabetic than in the control women. The heart rate rise also tended to be less in the diabetic women, resulting in a markedly smaller increase in cardiac output in this group (1.3 vs. 3.4 L/min, P less than .01). Left ventricular systolic function, wall thicknesses, or left atrial size did not differ between the groups at any point in the study. Minor collections of pericardial fluid were observed in 14 (76%) diabetic women and in 5 (45%) control women during the second and/or third trimester, but only 2 diabetic women had classic pericardial effusions. In conclusion, the normal hemodynamic adjustments to pregnancy seem to be impaired in women with IDDM. Preclinical diabetic cardiomyopathy and autonomic neuropathy may be involved in the observed alterations.
Diabetes Care
PMID:Impaired cardiac adjustment to pregnancy in type I diabetes. 352 13

To determine if cardiac autonomic neuropathy (CAN) contributes to diabetic cardiomyopathy, left ventricular function was assessed by resting and exercise radionuclide ventriculography (RVG) in 30 patients with long-standing insulin-dependent diabetes mellitus who had no clinical, electrocardiographic, or tomographic thallium scan evidence of heart disease. In 11 of 30 patients (37%), RVG revealed abnormal left ventricular performance. CAN was found in 91% of these patients. RVG was abnormal in 59% of patients with CAN and in only 8% of patients without CAN (P less than 0.005). There were significant reductions in mean (+/- SE) ejection fractions (EF) in patients with CAN at rest (62.8 +/- 2.2% vs. 75.2 +/- 2.5%; P less than 0.001) and with maximal exercise (65.8 +/- 2.6% vs. 80.9 +/- 2.3%; P less than 0.001) compared to patients without CAN. There was an inverse correlation between the autonomic function score and both resting EF (r = -0.53; P less than 0.002) and exercise EF (r = -0.55; P less than 0.002). Systolic function did not correlate with age, sex, duration or control of diabetes, microvascular complications, or plasma norepinephrine levels. Thus, approximately one third of our study population had evidence for depressed left ventricular function in the absence of ischemic heart disease, and the cardiac dysfunction was related to the severity of CAN. CAN may be a contributor to cardiac dysfunction in diabetes mellitus.
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PMID:Abnormal cardiac function in diabetic patients with autonomic neuropathy in the absence of ischemic heart disease. 371 Dec 60


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