Effects of exercise training and vitamin E on cardiac performance in aged rats

Aging is characterized by impaired contractile function in the heart. Meanwhile, during senescence the heart faces a high risk of free radical injury which may be a reason for development of myocardial dysfunction in the aged heart. To investigate this, we compared the effects of swim exercise training versus vitamin E treatment on age associated changes in intrinsic cardiac function in response to beta- adrenergic stimulation, induced ischemia and reperfusion. Rats were divided into a] control group b] exercise-trained group c] vitamin E treated group. Isolated hearts were studied in a Langendorff preparation for their intrinsic properties, and their responses to beta- adrenergic stimulation. After recovery the isolated hearts were subjected to global ischemia followed by reperfusion. The results showed that the exercise program adopted resulted in enhancement of time to peak tension response of aged hearts to beta- adrenergic stimulation. Following ischemia/reperfusion [I/R], such program enhanced half relaxation time. Treatment of the aged hearts with vitamin E maintained coronary blood flow and improved the inotropic cardiac reserves. Vitamin E proved to be cardioprotective against the toxic doses of catecholamines as well as the injury of post I/R on the heart. Coronary effluent from hearts of vitamin E _ treated rats had the significant highest level of nitrate compared to the other two groups when measured at 3.46 micro g dose of isoproterenol and at 30 min of reperfusion. Vitamin E enhanced cardiac responsiveness to beta- adrenergic stimulation, and protected the aged heart against I/R injury. Preservation of NO from being transformed to peroxynitrite by antioxidant action of vitamin E may have played a significant role. Swim- training program did not show promising cardio-protective effects against cardiac changes associated with the aging process

Effect of medical ozone therapy on diabetes-induced cardiac dysfunction

Diabetic metabolic dysregulation is accompanied by oxidative stress that could possibly lead to dysfunction in cardiac myocytes. The aim of this study was to elucidate the effect of controlled medical ozone therapy to diabetic rats on ischemia reperfusion insult in isolated rat hearts. Both long-term [12 weeks duration] and short-term [20 days duration] treatment were investigated. Rats of each duration were divided into non-diabetic control group and streptozotocin-induced diabetic group, the latter group being further divided into two subgroups, namely, a group receiving medical ozone and the other remaining untreated. Long-term groups were studied for the cardiac responses before and after ischemia reperfusion. Short-term groups were used to assess the degree of leukocytic adhesion to coronary endothelium. In both durations, serum levels of CPK and TNF-alpha were determined. Long-term ozone therapy to diabetic rats improved myocardial depression before and after ischemia reperfusion, with reduction in ischemia reperfusion injury. Short-term therapy resulted in an attenuating effect on leukocyte adherence to coronary vascular endothelial cells after ischemia-reperfusion. The present data show the cardioprotective effect of medical ozone therapy on ischemia reperfusion injury in diabetic rats. The reduction in TNF-alpha may represent a mechanism for such protection. Prohibiting leukocyte-endothelial adhesion and transmigration may be useful in decreasing leukocyte-dependent post-reperfusion injury

Oxidative preconditioning of medical ozone

Cardiac ischemic reperfusion injury is gaining importance due to rising of cardiac intervention procedures invoking transient ischemia, which requires trials of preconditioning strategies, A possible beneficial one could be the use of medical ozone, which is known to play a vital role in our well -being Therefore, the effect of small dose medical ozone on heart muscle and its possible protective effect on subsequent ischemia/ reperfusion injury was evaluated. Animals included in the present study were allocated into three groups: unconditioned control rats [group I], two months-ozonepreconditioned rats [group II], and three months-ozone-preconditioned rats [group III]. Rats were injected i.p. with small doses of ozone twice weekly. At the end of the experimental period, half the rats in each group were injected with heparin, a blood sample was taken for determination of plasma malondialdehyde [MDA] and the heart excised and used for isolated heart study. A blood sample was collected from the other half in each group for determination of serum glucose and the heart excised and sent for histological examination. Isolated heart study was carried out according to modified Langendorff technique. After recording basal cardiac activity, global ischemia was induced by stoppage of perfusion for 30 minutes followed by resumption of flow for another 30 minutes, and cardiac activity then recorded. The results revealed signifcant reduction in intrinsic inotropy of hearts isolated from unconditioned control rats after ischemia/ reperfusion [I/R], evidenced by significant decrease in tension generation per unit time [PT/t] after I/R in these rats, together with prolongation, of half relaxation time, insignificant change of intrinsic chronotropic activity and myocardial flow rate after I/R. Two months-medical ozone-preconditioning resulted in correction of the impaired intrinsic inotropy after I/R seen in unconditioned control rats, with enhancement of diastolic function. However, three months- medical-ozone preconditioning did not protect the hearts isolated from these rats from systolic dysfunction after I/R, though the diastolic function was significantly improved after I/R compared to unconditioned control rats. Serum glucose was decreased and plasma malondialdehyde was significantly increased in both the two-and three-months ozone-preconditioned rats. Histological examination of heart muscle revealed increased mitochondria! density in ozone preconditioned rats which was more marked in the two months-ozone-treated rats

Estrogen replacement therapy in OVX-STNx rats and its nephroprotective role against progression of renal failure

Inspite of estrogen replacement therapy being extensively used in clinical and experimental studies without renal impairment, there are no long-term studies concerning estrogen replacement in chronic renal failure. This study was performed to explore whether estrogen has a nephroprotective role against progression of renal failure. This study was carried out on 41 adult female albino rats, that were allocated into 3 groups; Group 1 [n = 10] sham-operated rats, that received the solvent [sesame oil] and used as control group, Group II [n = 17], ovariectomized-subtotal nephrectomized rats [OVX-STNx] without treatment, that received the solvent, group III [n = 14], OVX-STNx rats treated with estrogen, subcutaneous [s.c.] at a dose of 30 micro g/kg/day for 10 weeks, started on the second day after ovariectomy. Mean Blood pressure was measured on the day of sacrifice. Blood urea nitrogen [BUN], serum creatinine, malondialdehyde [MDA] and platelet aggregation were estimated. Kidneys were excised and examined histologically. The results of the present study showed that untreated OVX-STNx rats showed significant elevation in mean blood pressure compared to treated OVX-STNx rats [129 +/- 2.2 versus 97 +/- 3.2 mmHg]. The untreated OVX-STNx rats showed significant elevation in BUN and serum creatinine levels compared to sham-operated rats [85.9 +/- 4.0 versus 19.4 +/- 1.6 mg/dl; and 2.6 +/- 0.13 versus 0.16 +/- 0.02 mg/dl, respectively], while, the treated OVX-STNx group showed significant reduction in BUN and serum creatinine levels, compared to untreated OVX-STNx group [24.8 +/- 1.6 versus 85.9 +/- 4.0 mg/dl; and 0.38 +/- 0.04 versus 2.6 +/- 0.13 mg/dl, respectively]. In addition, serum MDA level was elevated in untreated OVX-STNx group compared to sham-operated and to treated group [6.6 +/- 0.4 versus 3.6 +/- 0.3 and 4.8 +/- 0.3 /micro mol/L, respectively]. Also, ADP-stimulated platelet aggregation showed significant reduction in untreated OVX-STNx group in comparison to sham-operated and to treated group [46.8% +/- 2.6 versus 76.5% +/- 1.8 and 65.1% +/- 3.6 respectively]. Histological examination of the remnant kidney models in untreated OVX-STNx group showed a picture of focal glomerulosclerosis, this finding was minimally seen in treated OVX-STNx group