In our study, these results suggest that MF exposure regulates the isometric contractile characteristics of the soleus and EDL muscles of rats with diabetes, positively.

No abstract

In this study, we investigated the effects of salt loading on sympathetic pressor activity, cardiac autonomic activity, mean arterial pressure (MAP), heart rate (HR) and on the relations between them in anesthetized two-kidney, one clip (2K1C) hypertensive rats. We submitted rats to either renal artery clipping or sham operation. Distilled water or 0.5 % NaCl was given orally to the clipped and sham-operated control rats for 4 weeks. Then, MAP and HR differences between pre-and post-autonomic blockade were evaluated as indexes of sympathetic pressor and cardiac autonomic activity, respectively. The autonomic blockade decreased MAP to the similar levels in all groups (between 81.7±7.6 -87.3±7.1 mmHg). Sympathetic pressor activity was greater in the clipped rats than in its sham-operated controls only under salt loading (55.3±6.2 vs. 37.0±4.1 mmHg, p<0.05). Cardiac autonomic activity was, predominantly, sympathetic and more in the clipped group than in the sham-operated rats under distilled water (48.3±8.6 vs. 19.7±7.0 beats/min, p<0.05) but not under salt loading. Salt loading inverted the relationship between HR and cardiac autonomic activity in 2K1C hypertensive rats (r=-0.76, p=0.046 vs. r=0.89, p=0.019). These results suggest that salt loading may have augmented the effect of renovascular constriction on MAP by affecting the sympathetic pressor activity and the relation between cardiac autonomic activity and HR in 2K1C hypertensive rats.

The Frog Embryo Teratogenesis Assay-Xenopus (FETAX) was used to assess the teratogenic potential of two tocolytics. Embryos of the South African clawed frog, Xenopus laevis, were exposed to ritodrine or nifedipine. Exposure media were changed and monitored at 24-hour intervals. The 96-hour LC50 (Lethal concentration), the 96-hour EC50 (Malformation), and the No Observable Adverse Effect Concentrations (NOAEC) and the Lowest Observable Adverse Effect Concentration (LOAEC) for mortality, malformation and length were determined for each drug. Nifedipine was determined to be the more toxic and teratogenic than ritodrine, with a LC50 of 0.606 µg/L, an EC50 of 0.006 µg/L, and a teratogenicity Index (TI) value (LC50/EC50) of 101. On the other hand, the LC50 of ritodrine was 28.571 mg/L. In addition; the LC50, EC50 and TI values for nifedipine in the 5 mg/L ritodrine + nifedipine combination group were determined as 1.050 µg/L, 0.868 µg/L and 1.5 respectively. For ritodrine, the NOAEC and LOAEC values were determined as 2 mg/L and 4 mg/L, respectively. For the nifedipine and the ritodrine + nifedipine groups; while the LOAEC values of these groups were 0.0001 µg/L and 0.1 µg/L, respectively. NOAEC value couldn't be determined. Our results demonstrated that nifedipine administration was associated with higher levels of teratogenic and toxic effects. However, the ritodrine + nifedipine combination form reduced the toxic and teratogenic effects of nifedipine on Xenopus embryos. Further studies should be conducted in order to investigate the optimal combination concentrations of these substances for the treatment of preterm labor.

RRM in combination with 0.5% NaCl loading led to a decrease in the sensitivity of full baroreflex and of the parasympathetic component of baroreflex. Changes in plasma Na and K levels, due to NaCl loading, may have contributed to the decrease in baroreflex sensitivities and IHR but had no effect upon MAP in RRM rats.