Effects of physical training on end-diastolic volume and myocardial performance of isolated rat hearts.

Bersohn, Malcolm; Scheuer, James

doi:10.1161/01.res.40.5.510

Cited by 72 publications

(37 citation statements)

References 17 publications

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“…The effect of exercise on muscle mass in hypertension is controversial with various studies indicating both hypertrophy as a result of exercise (Barnard, et al 1980) and a reduction in hypertrophy (Hinderliter, et al 2002). There were others however, indicating no significant change in muscle mass due to exercise (Bersohn and Scheuer 1977). Our findings here tend to agree with the latter observation.…”

Section: Discussionsupporting

confidence: 82%

Volumetric changes in the components of left ventricle myocardium of spontaneously hypertensive rats following exercise and ACE inhibitor treatment

Inuwa¹,

Hassan²,

Ziada³

2006

African Journal of Biomedical Research

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This study was designed to test the possible effects of a combination of physical and pharmacological therapy intervention on myocardial structure of the left ventricle in spontaneously hypertensive rats (SHR). Forty 12 weeks old spontaneously hypertensive rats were divided into four groups of sedentary, Sed as controls, exercise only , (Exer), lisinopril only 20mg/kg/day, ( Lis) , and exercise + lisinopril, (LisExer). Exercise training was performed on a treadmill (5m/min.) for 60 minutes/day, 5 days/week for 10 weeks. At the end of 10 weeks, all the rats were terminally anaesthetised, the heart was arrested in diastole by intravenous procaine and whole animal perfusion fixation through the abdominal aorta was carried out using Karnovsky's fixative (Ph 7.24). The heart was removed and left ventricle plus the interventricular septum was serially sectioned at a thickness of three millimetres. One piece was randomly chosen, and embedded in JB4 resin. Six sections were obtained from each block, stained with toluidine blue:acid fucin. Measurement of volume fraction V f , of myocardial components was carried out using Histometrix MIL6 Ver 1.0 stereology software ( Kinetic imaging Ltd.). Mean volume fraction, V f of capillaries in Sed. group was 0.114 ± 0.01 (SEM). This was significantly increased in LisExer group. The volume fraction of muscle in Sed group was 0.795 ± 0.02 (SEM). This was significantly decreased in Lis but unchanged in Exer group. Capillaries V f was significantly higher in LisExer as compared to Lis or Exer groups (p<0.05). Muscle V f was not different between LisExer and Lis groups. The outcome of these changes could well be a better enhancement of cardiac performance in hypertension by combined exercise and ACE inhibitor treatment than either of the interventions alone.

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Section: Discussionsupporting

confidence: 82%

Volumetric changes in the components of left ventricle myocardium of spontaneously hypertensive rats following exercise and ACE inhibitor treatment

Inuwa¹,

Hassan²,

Ziada³

2006

African Journal of Biomedical Research

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“…This ventricular pressure-function curve (32) is a valid index of left ventricular contractility if there is no change in left ventricular compliance. Physical training does not alter left ventricular compliance (33). Thus, the increase in the slope of the pressure-function curve (left ventricular function index in Fig.…”

Section: Resultsmentioning

confidence: 89%

“…3) could be used to indicate that myocardial contractility increased in the dobutamine and exercise groups. Other investigators have shown that the mechanical performance of the heart is improved in physically conditioned animals (4,33,34), but the biochemical adaptation in cardiac muscle responsible 'for the increase in myocardial contractility has not been fully elucidated (1,24,35).…”

Section: Resultsmentioning

confidence: 99%

Conditioning Effects of Chronic Infusions of Dobutamine

Liang¹,

Tuttle²,

Hood³

et al. 1979

J. Clin. Invest.

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A B S T R A C T We studied the conditioning effects ofchronic infusion of dobutamine and exercise training in three groups of chronically instrumented dogs. One group was infused with normal saline, a second group was infused with dobutamine (40 ,ug/kg per min), and the third group was exercised on a treadmill at 4 mph, up a 100 incline. Each group was either infused or exercised for 2 h a day, 5 d a week for 5 consecutive wk. Resting heart rate and arterial blood lactate concentration, measured at weekly intervals, decreased progressively in the dobutamine and exercise groups, but not in the group that received normal saline infusion. Cardiovascular responses to submaximal treadmill exercise were not changed by 5 wk of normal saline infusion. However, the increases in heart rate, cardiac output, mean aortic blood pressure, arterial blood lactate, plasma renin activity, and norepinephrine concentration during exercise were significantly smaller after 5 wk of conditioning with either dobutamine or exercise training. After conditioning, the increases in arteriovenous oxygen difference during exercise were larger in the latter two groups, but the increases in total body oxygen consumption did not differ before and after conditioning.To assess ventricular function, we intravenously infused methoxamine both before and after conditioning. The slope of the line that related systolic aortic blood pressure and mean left atrial pressure increased in the animals conditioned with either dobutamine or exercise, indicating enhanced myocardial contractility. Left ventricular blood flow was lower in these two groups of animals than it was in the normal saline group. Left ventricular weight did not differ among the three groups.Our results show that chronic infusion of dobutamine produced cardiovascular and metabolic conditioning effects like those produced by exercise training, and further suggest that sympathetic stimulation during exercise plays a role in physical conditioning.

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“…In the first series ofexperiments hearts were perfused for analysis of pump function, myocardial function, and cardiac metabolism. Full descriptions of the isolated working rat heart apparatus have been published previously (1 [1][2][3][4][5][6][7][8][9][10][11][12][13]. The Cardiac function was assessed at two levels of preload at each of three levels of afterload.…”

Section: Methodsmentioning

confidence: 99%

“…A full description of this method and the validation for estimating ventricular volumes has been published previously (13). For (12).…”

Section: Methodsmentioning

confidence: 99%

Cardiac conditioning ameliorates cardiac dysfunction associated with renal hypertension in rats.

Schaible¹,

Ciambrone²,

Capasso³

et al. 1984

J. Clin. Invest.

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Abstract. To explore the effect of physiologic hypertrophy superimposed on pathologic hypertrophy, hearts from female control rats (C), renal hypertensive rats (H), rats conditioned with a 10-12 wk swimming program (Sw), and hypertensive rats trained by the swimming program (H-Sw) were perfused in an isolated working rat-heart apparatus. Systolic blood pressure was -100 mmHg in C and Sw and was 160 mmHg in H and HSw. The swimming program had no effect on blood pressure. Compared with C, heart weight was increased by 30% in Sw, 47% in H, and 77% in H-Sw. At high preload and afterload, cardiac output (milliliters per gram dry LV weight) was decreased in H, increased in Sw, and partially restored towards normal in H-Sw. Ejection fraction, percent fractional shortening, and mean velocity of circumferential fiber shortening were enhanced in Sw, depressed in H, and normalized in H-Sw when compared with C. Coronary flow and myocardial oxygen consumption in this series of hearts were depressed in H, with no restoration in H-Sw, but coronary effluent lactate/ pyruvate ratios were only elevated in the hearts of H-Sw. Coronary vascular responses were examined in a second series of experiments which used microspheres. In this series, the depressed coronary flow observed in H was partially restored towards normal in H-Sw and the inner/ outer myocardial flow ratio was normal when hearts were

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Effects of physical training on end-diastolic volume and myocardial performance of isolated rat hearts.

Cited by 72 publications

References 17 publications

Volumetric changes in the components of left ventricle myocardium of spontaneously hypertensive rats following exercise and ACE inhibitor treatment

Volumetric changes in the components of left ventricle myocardium of spontaneously hypertensive rats following exercise and ACE inhibitor treatment

Conditioning Effects of Chronic Infusions of Dobutamine

Cardiac conditioning ameliorates cardiac dysfunction associated with renal hypertension in rats.

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