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Fluid consumption, electrolyte excretion and heart remodelling in rats with myocardial infartc maintained on regular and high sodium intake

100%

Cudnoch-Jedrzejewska A., Szczepanska-Sadowska E., Dobruch J., Morton M., Koperski L., Wasiutynski A., Wsol A., Kowalewski S.

Journal of Physiology and Pharmacology

2005

tom 56

nr 4

The purpose of the study was to determine effect of high sodium intake on fluid and electrolyte turnover and heart remodeling in the cardiac failure elicited by myocardial infarction (MI). The experiments were performed on four groups of Sprague Dawley rats maintained on food containing 0.45% NaCl and drinking either water (groups 1, 2) or 1% NaCl (groups 3, 4). Groups 1 and 3 were sham-operated while in groups 2 and 4 MI was produced by the coronary artery ligation. In each group food and fluid as well as sodium intake, urine (Vu), sodium (UNaV), potassium (UKV) and solutes (UosmV) excretion were determined before and four weeks after the surgery. Size of the infarct, left ventricle (LV) weight and diameter of LV and right ventricle (RV) myocytes were determined during post-mortem examination. Before the surgery groups 3 and 4 ingested significantly more fluid and sodium, had higher Vu, UNaV, UKV and UosmV than the respective groups 1 and 2. In groups 2 and 4 MI resulted in significant decrease in Vu, UNaV and UosmV in comparison to the pre-surgical level. In Group 4 MI resulted also in a significant decrease of food and sodium intake. The MI size did not differ in groups 2 and 4 while diameter of LV myocytes was significantly greater in groups 2 and 4 than in groups 1 and 3, and in group 4 than in group 2. The study reveals that prolonged high sodium consumption increases fluid and electrolyte turnover both in the sham and in the MI rats and that the MI causes decrease in food and sodium intake in rats on high but not on regular sodium intake. In addition high sodium diet promotes development of greater post-MI hypertrophy of the LV myocytes.

Enhanced expression of mineralocorticoid receptors in the heart after the myocardial infarct in rats

80%

Milik E., Szczepanska-Sadowska E., Maslinski W., Cudnoch-Jedrzejewska A.

Journal of Physiology and Pharmacology

2007

tom 58

nr 4

Increasing evidence suggests that enhanced stimulation of the heart and kidney by mineralocorticoids plays significant role in development of the post-infarct cardiac failure. Because increased synthesis of mineralocorticoid receptors (MR) is one of the putative factors determining pathogenic effects of mineralocorticoids we decided to determine whether the myocardial infarct results in an enhanced expression of MR mRNA and MR protein. To this end male Sprague-Dawley rats were subjected either to ligation of the left coronary artery or to sham surgery. After four weeks expressions of MR mRNA and MR protein were evaluated in both groups of rats in the left (LV) and right (RV) ventricle walls, and in the renal cortex and renal medulla by means of semiquantitative PCR and Western blotting methods. Coronary ligation resulted in the myocardial infarction encompassing 30.2% ± 1.9% (range 23-40%) of the left ventricle wall. In the infarcted rats expression of MR mRNA was significantly greater than in the sham-operated rats, both in the LV (P<0.02) and in the RV (P<0.005). In the left but not in the right ventricle increased MR mRNA expression was associated with significant increase in expression of MR protein (P<0.001). In the renal cortex and renal medulla MR mRNA and MR protein expression in the infarcted and the sham-operated rats did not differ. The study reveals that during the post-infarct state expression of MR mRNA is elevated in both cardiac ventricles while expression of MR mRNA protein is increased only in the left ventricle. The results suggest that the enhanced expression of mineralocorticoid receptors may contribute to enhanced effects of mineralocorticoids in the heart during the post-infarct state.

Ograniczanie wyników

2 Journal of Physiology and Pharmacology

2 Cudnoch-Jedrzejewska A.

2 Szczepanska-Sadowska E.

1 Dobruch J.

1 Koperski L.

1 Kowalewski S.

1 Maslinski W.

1 Milik E.

1 Morton M.

1 Wasiutynski A.

1 Wsol A.

1 2007

1 2005

Wyniki wyszukiwania

Fluid consumption, electrolyte excretion and heart remodelling in rats with myocardial infartc maintained on regular and high sodium intake

Enhanced expression of mineralocorticoid receptors in the heart after the myocardial infarct in rats