9 results on '"Schaible TF"'
Search Results
2. Chronic swimming reverses cardiac dysfunction and myosin abnormalities in hypertensive rats.
- Author
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Schaible TF, Malhotra A, Ciambrone GJ, and Scheuer J
- Subjects
- Adenosine Triphosphatases metabolism, Animals, Cardiomegaly etiology, Coronary Circulation, Female, Hypertension, Renovascular complications, Hypertension, Renovascular physiopathology, In Vitro Techniques, Physical Education and Training, Rats, Rats, Inbred Strains, Swimming, Heart physiopathology, Hypertension, Renovascular therapy, Myosins metabolism, Physical Exertion
- Abstract
The purpose of this study was to determine whether a chronic swimming program could reverse the decreased cardiac function and altered myosin biochemistry found in hearts of rats with established renal hypertension. Ten wk after the onset of hypertension [midpoint (m)], hearts from normotensive controls (C) and hypertensives (H) were studied in an isolated working heart apparatus, and myosin biochemistry was analyzed. Half of the control and hypertensive animals were then subjected to a 10-wk swimming program (Sw) and their hearts were compared with those from age-matched sedentary rats. Body weight was no different at the midpoint of the study between Cm and Hm or at the end point (e) of the study among Ce, Swe, He, or H-Swe. Swimming had no effect on blood pressure in either normotensive or hypertensive rats. Dry heart weight was increased by 46% in Hm compared with Cm and by 36% in He, 21% in Swe, and 61% in H-Swe when compared with Ce. Hypertension was associated in both the mid- and end-point studies, with decreases in coronary flow, stroke work (both per gram left ventricle), ejection fraction, and midwall fractional shortening. In addition, actin-activated myosin adenosinetriphosphatase (ATPase) activity was decreased in Hm and He associated with an increase in the content of the V3 myosin isoenzyme. Although the coronary deficit was not corrected in H-Swe, stroke work, ejection fraction, and fractional midwall shortening were normalized compared with control hearts. Myosin ATPase activity and the myosin isoenzyme distribution were similarly restored in H-Swe.(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1986
- Full Text
- View/download PDF
3. Cardiac function in hypertrophied hearts from chronically exercised female rats.
- Author
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Schaible TF and Scheuer J
- Subjects
- Animals, Blood Pressure, Cardiac Volume, Female, Physical Conditioning, Animal, Rats, Sex Factors, Cardiomegaly physiopathology, Heart physiopathology, Myocardial Contraction, Physical Exertion
- Abstract
Physiological cardiac hypertrophy was produced in female rats by subjecting them to a swimming program for 8 wk. Conditioned rats (C) had body weights similar to sedentary control rats (S), but hearts from C weighed 33% more than hearts from S. Heart function was assessed in an isolated working-heart apparatus at similar heart rates and aortic diastolic pressures and over a range of 5-20 cmH2O left atrial filling pressure (LAP). At any given LAP, absolute values for cardiac output and coronary flow were greater (p less than 0.001) in C than S, but when these values were normalized for dry left ventricular (LV) weight, no differences were observed. Peak LV systolic pressure and ejection fraction were greater (p less than 0.01) in C than S at all LAP. Derived measures of contractility calculated at the midwall demonstrated greater (p less than 0.01) velocity and extent of circumferential fiber shortening in C compared with S. Therefore, chronic swimming in female rats leads to enhanced contractile performance of the left ventricle despite a marked degree of hypertrophy. These results contrast with our earlier observations in female rats trained by running where neither hypertrophy nor enhanced function were observed.
- Published
- 1981
- Full Text
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4. Early increases in coronary vascular reserve in exercised rats are independent of cardiac hypertrophy.
- Author
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Buttrick PM, Levite HA, Schaible TF, Ciambrone G, and Scheuer J
- Subjects
- Animals, Body Weight, Female, Male, Organ Size, Perfusion, Rats, Rats, Inbred Strains, Sex Factors, Time Factors, Cardiomegaly physiopathology, Coronary Circulation, Physical Exertion
- Abstract
To evaluate the relationship between the physiological cardiac hypertrophy associated with physical training and the increases in vascular capacitance associated with this stimuli, male and female rats trained by a swimming program were studied. Both sexes were used so that the coronary vascular response to exercise could be studied in the presence (females) and absence (males) of cardiac hypertrophy. Coronary vascular reserve was assessed in isolated retrograde buffer-perfused hearts under conditions of minimal coronary resistance (15 microM adenosine or anoxia). Both groups demonstrated an increase in coronary vascular reserve after 8 wk of exercise swim training, male animals increasing flow (per g of myocardium) by 15% and females by 18%. When the time course of this response was compared in female animals with the time course of the development of myocardial hypertrophy, it was evident that the vascular changes occurred early, greater than 80% of the response was seen within the first 10 days of exercise, compared with an approximately 35% increase in cardiac mass. These data suggest that the vascular response to exercise swim training is independent of the hypertrophic response and further that the increase in coronary vascularity is an early event in the cardiac adaptation to a physiological load.
- Published
- 1985
- Full Text
- View/download PDF
5. Abnormal cardiac biochemistry in spontaneously diabetic Bio-Breeding/Worcester rat.
- Author
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Malhotra A, Mordes JP, McDermott L, and Schaible TF
- Subjects
- Adenosine Triphosphatases metabolism, Animals, Cardiomyopathies etiology, Diabetes Mellitus, Type 1 complications, Diabetes Mellitus, Type 1 genetics, Female, Isoenzymes, Male, Rats, Rats, Inbred BB metabolism, Diabetes Mellitus, Type 1 metabolism, Myocardium enzymology, Rats, Inbred BB genetics, Rats, Inbred Strains genetics
- Abstract
Diabetes produced by injection of alloxan or streptozotocin results in cardiac dysfunction in rats that is associated with lower cardiac contractile protein ATPase activity. The purpose of this investigation was to examine cardiac myosin biochemistry in the Bio-Breeding Worcester (BB/W) rat, a strain in which diabetes occurs spontaneously and closely resembles insulin-dependent diabetes in humans. Hearts from diabetic BB/W rats were studied at 1, 4, and 7 mo after the onset of diabetes and were compared with age-matched BB/W rats that were bred for resistance to diabetes. Calcium-stimulated myosin ATPase activity was significantly decreased after 4 and 7 mo of diabetes, and actin-activated myosin ATPase was significantly depressed at all time points. Differences between hearts from control and diabetic animals increased with the duration of diabetes. Closely associated with reductions in myosin ATPase activity in the diabetes was a shift in the isomyosin content from the normally predominant V1 to the V3 isoenzyme. Thus diabetes that results from genetic causes leads to depressed myosin enzymatic activity in the rat. Furthermore, since previous studies have shown that BB/W diabetic rats do not develop hypothyroidism, the present results support the view that altered thyroid function does not mediate the abnormalities in cardiac contractile proteins in diabetes.
- Published
- 1985
- Full Text
- View/download PDF
6. Cardiac responses to exercise training in male and female rats.
- Author
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Schaible TF, Penpargkul S, and Scheuer J
- Subjects
- Animals, Coronary Circulation, Electron Transport Complex IV metabolism, Female, Heart anatomy & histology, Male, Muscles enzymology, Myocardium metabolism, Oxygen Consumption, Perfusion, Rats, Sex Factors, Stroke Volume, Heart physiology, Physical Conditioning, Animal
- Abstract
The purpose of the present study was to determine if contractile function adapts to physical training in the same way in hearts of male and female rats. Male and female rats were trained with a running program sufficient to cause equal increases in cytochrome oxidase activity in gastrocnemius muscles in both groups. Hearts were then studied in an isolated perfused working rat heart apparatus with varying preloads and fixed afterloads. Five groups were studied: 1) free-eating sedentary males (MS-FE); 2) running males (MR); 3) sedentary females (FS); 4) running females (FR); and 5) food-restricted sedentary; males (MS-FR). Heart weights were similar in MS-FE and MR and in FS, FR, and MS-Fr. Stroke work, stroke volume, coronary flow, and myocardial oxygen consumption were significantly higher in MR than in MS-FE but were almost identical in FR and FS. MS-FR showed stroke work, stroke volume, and ejection fractions that were similar to MR but higher than MS-FE and both female groups. Thus when hearts of equal weights were compared, a training effect was only seen in males. These results suggest that despite similar skeletal muscle adaptations, hearts of male rats adapt to physical training by running with improved intrinsic performance, whereas hearts of female rats do not.
- Published
- 1981
- Full Text
- View/download PDF
7. Combined effects of hypertension and conditioning on coronary vascular reserve in rats.
- Author
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Buttrick PM, Schaible TF, and Scheuer J
- Subjects
- Animals, Blood Pressure, Body Weight, Female, Hypertension pathology, Rats, Rats, Inbred Strains, Regional Blood Flow, Swimming, Vascular Resistance, Coronary Vessels physiopathology, Hypertension physiopathology, Physical Conditioning, Animal
- Abstract
To evaluate the combined effects of cardiac overload imposed by hypertension and chronic swim training on coronary vascularity, female rats were made hypertensive by unilateral renal artery stenoses and were exercised in an 8- to 10-wk swimming program. Maximal coronary flow was assessed in isolated retrograde buffer-perfused hearts under conditions of minimal coronary resistance (15 microM adenosine or anoxia). Sedentary normotensive animals, sedentary hypertensive animals, and normotensive animals exposed to a swimming program were also studied. Swimming was associated with an 18% increase in heart weight and with increases in both absolute (ml/min) and relative (ml X g-1 X min-1) maximal coronary flow. Hypertension was associated with a 32% increase in heart weight but with a decrease in absolute and relative coronary flow compared with controls. The combined stimuli resulted in a 63% myocardial hypertrophy and a 19% increase in absolute flow. Relative coronary flow (g tissue-1) was similar in hearts from hypertensive sedentary animals and hypertensive swimmers. These data indicate that the coronary vascular deficit that accompanies the cardiac hypertrophy of hypertension is not worsened by the superimposition of an exercise load that exaggerates the hypertrophy.
- Published
- 1986
- Full Text
- View/download PDF
8. Effects of pregnancy on cardiac function and myosin enzymology in the rat.
- Author
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Buttrick PM, Schaible TF, Malhotra A, Mattioli S, and Scheuer J
- Subjects
- Actins physiology, Animals, Body Weight, Coronary Circulation, Female, Heart anatomy & histology, Isoenzymes physiology, Myocardial Contraction, Organ Size, Pregnancy, Rats, Adenosine Triphosphatases metabolism, Heart physiology, Myocardium enzymology, Pregnancy, Animal
- Abstract
Previous studies of cardiac function during pregnancy, while suggesting that this condition is associated with improved myocardial contractility, have been biased by the altered in vivo loading conditions. Therefore, we have investigated intrinsic cardiac function and contractile protein biochemistry during pregnancy in isolated rat hearts under controlled loading conditions. Animals were impregnated and studied after 1 and 3 wk and 2-3 days postpartum (gestation 21 days). The data show that hearts from pregnant animals (at 3 wk) had improved contractile performance as manifested by an 11% increase in fractional shortening, a 20% increase in velocity of circumferential fiber shortening, and an upward-shifted force-velocity relationship. These findings were paralleled by a 16% increase in Ca2+-activated myosin and an 11% increase in actin-activated ATPase activities. Thus pregnancy in the rat is associated with slightly improved cardiac contractility and biochemistry. This may relate directly to the hormonal status of the pregnant animal or to the effects of chronic volume overload.
- Published
- 1987
- Full Text
- View/download PDF
9. Effects of graded insulin therapy on cardiac function in diabetic rats.
- Author
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Rubinstein M, Schaible TF, Malhotra A, and Scheuer J
- Subjects
- Animals, Blood Glucose analysis, Blood Pressure, Coronary Circulation, Insulin therapeutic use, Isoenzymes, Male, Myocardial Contraction drug effects, Myocardium enzymology, Oxygen Consumption, Rats, Rats, Inbred Strains, Streptozocin, Diabetes Mellitus, Experimental drug therapy, Heart drug effects, Insulin administration & dosage
- Abstract
To determine the effects of graded insulin therapy on cardiac function and biochemistry, rats were made diabetic by streptozotocin (50 mg/kg) and subsequently treated with either 3 U of insulin per day (D3) or 5 U/day (D5) and compared with untreated diabetic rats (D phi) and a nondiabetic control group (C). Blood glucose, water consumption, and heart and body weights in D3 and D5 showed dose-dependent responses between those of D phi and C. Cardiac function was studied at similar heart rates and similar left atrial and aortic pressures in an isolated working heart apparatus. Hearts from D phi showed significant decreases in end-diastolic pressure, peak left ventricular systolic pressure, and positive dP/dt, whereas these values in D3 and D5 were similar to those in C. The isovolumic relaxation period was significantly longer in the D phi group, intermediate between D phi and C in D3, and the same in D5 and C. Ca2+-ATPase activity of myosin and actin-activated Mg2+-ATPase activity was depressed in D phi, partially corrected in D3, and completely corrected in D5. Myosin isoenzyme distribution displayed a shift from the predominant V1 pattern observed in C to a predominant V3 pattern in D phi. Treatment with 3 U of insulin per day partially corrected the isoenzyme abnormality, and treatment with 5 U/day restored the isoenzyme distribution to normal. These results indicate that gross cardiac contractile function can be normalized with insulin dosages that are not sufficient to correct hyperglycemia, polydipsia, or body and heart weight.(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1984
- Full Text
- View/download PDF
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