Effect of exposure to electromagnetic field on some aspects of hepatic function in rats

Exposure to electromagnetic fields [EMF] may pose health risks and cell damage in various tissues, among the most susceptible tissues to EMF exposure being the liver. It was, thus, intriguing to investigate the possible effect of whole body exposure to EMF of mobile phones on some parameters reflecting the liver function. This study was performed on 111 albino rats of both sexes. Rats were divided into 2 main groups: 4 weeks exposure group [group I] and 8 weeks exposure group [group II]. Rats in each group were further subdivided into 4 subgroups, namely; rats not exposed to EMF of mobile phone [control groups, Ic and IIc], rats exposed to EMF of mobile phone for 1 hour/day [groups I[1] and II[1]], for 2 hours/day [groups I[2] and II[2]] and for 3 hours/day [groups I[3] and II[3]]. Exposure to EMF did not result in any significant change in plasma activities of both alanine aminotransferase [ALT] and aspartate aminotransferase [AST] in all exposed rats compared with their matched control. However, there was significant prolongation of both prothrombin time [PT] and activated partial thromboplastin time [PTT] accompained by significant elevation of hepatic malondialdehyde [MDA] content and reduction of nitric oxide [NO] content in hepatic tissue, the changes being more marked with increase in the duration of exposure. Microscopic examination of the liver tissue showed hepatocytic vacuolizations, irregular diameters of sinusoidal lumens, inflammatory cellular infiltrations and reduced glycogen content, the changes becoming intense with prolongation of the EMF exposure period. Exposure to EMF of mobile phones poses a risk factor for liver dysfunction, and, therefore, long term or excessive use of mobile phones better be avoided

Effects of oral administration of a mixture of amino acids on cardiac function in aged rats

Aging is associated with cardiovascular changes, and with impaired protein synthesis in muscles, including cardiac muscle secondary to increased risk of serious nutritional deficiencies coupled with reduced protein intake. The present study aimed at evaluating the effect of oral supplementation with a mixture of amino acids on cardiac inotropic and chronotropic properties of isolated hearts of aged rats and their responsiveness to beta- adrenergic stimulation. Rats were divided into 2 groups, a control group and amino acids [AAs] supplemented group. Isolated hearts were studied in a Langendorff apparatus for their intrinsic properties, and their responses to beta - adrenergic stimulation. At the end of the experiment, the isolated hearts were blotted dry, weighed and some hearts were subjected to histological study. The results showed that AAs-supplementation significantly increased the body weight, the absolute weights of right ventricle, left ventricle and whole heart as well as their relative weights to body weight. The baseline, maximum response to ISO infusion and the delta change of peak tension, the time taken to reach the peak tension and the maximum rate of tension development were significantly increased in hearts isolated from AAs supplemented rats compared to hearts isolated from the control rats. This was associated with non significant changes in heart rate, half relaxation time as well as myocardial flow rate. Histological studies revealed that AAs supplementation attenuates degenerative changes, decreases fibrosis and increases glycogen content of the hearts of the aged rats. Exogenous supplements of amino acids mixture could be a valid therapeutic strategy to improve mechanical performance of cardiac muscle in the elderly. Further research is recommended to explore the usefulness of AAs in cardiovascular disorders associated with systolic dysfunction

Effect of changes in nitric level oxide on myometrial contractility in pregnant and non-pregnant rats

Nitric oxide [NO] has been recognized as a molecule that shares in regulation of the reproductive system physiology. The present study aimed to investigate the effects of NO excess and NO deficiency on spontaneous myometrial contractions and on myometrial responsiveness to oxytocin as well, in both non-pregnant and late pregnant rats. Female adult rats were divided into two main groups: estrogen-primed non-pregnant model and time-mated late pregnant model. Rats in each model were divided into three groups: a control group, L-arginine-treated group and L-NAME-treated group. Myometrial strips taken from the different groups were suspended in organ bath containing Krebs' solution, gassed with 95% O2 and 5% CO2 for recording of isometric contractions. Spontaneous uterine motility was recorded, followed by oxytocin addition for recording of myometrial responsiveness to this hormone. Serum nitrate level was determined in all rats. L-arginine supplementation caused a significant increase in serum nitrate levels in both rat models, accompanied by decreased spontaneous myometrial contractility and attenuation of the stimulatory effect of oxytocin in both non-pregnant and pregnant rats, compared to the control values. The predominating effect in the non-pregnant model was on the average force, and in the pregnant model on the frequency of contraction. Following treatment with L-NAME. serum nitrate was significantly decreased, yet the spontaneous myometrial contractility and its responsiveness to oxytocin were non-significantly changed in both non-pregnant and pregnant rats, compared to the control group. The NO donor L-arginine has proved to have an inhibitory effect on both spontaneous and oxytocin-induced myometrial contractions, when administered in vivo, in both non-pregnant and late pregnant states, establishing the importance of the L-arginine/NO system as a uterine smooth muscle relaxant. L-arginine could, therefore, provide a useful therapeutic measure for conditions with pathological uterine contractility, like dysmenorrhea or preterm labor, taking into consideration that increased NO attenuates myometrial responsiveness to oxytocin