Effects of photodynamic treatment on biological antioxidant systems in rats.

Effects of photodynamic treatments on inherent antioxidant metabolites and cellular defence enzymes have been investigated in rats. Wistar rats were grouped into untreated controls, light controls, hematoporphyrin derivative (Hpd) (treated with 5 and 10 mg Hpd/kg body weight and kept in dark) and sets treated with both Hpd and red light (dose 172 and 344 j/m2 ). After 2, 24, 48 and 72 hr of Hpd injection the rats sacrificed, livers quickly excised to analyze Hpd uptake, activities of enzymes like catalase, GSH-Px and antioxidants like GSH, vitamin A, vitamin E and vitamin C. The results showed that the loss of Hpd from liver as a function of post- injection time was non- linear. An increased generation of lipid radicals was observed in the groups treated with 5 mg Hpd and higher dose of light and in groups treated with 10 mg Hpd at both the doses of light. Combination of light and Hpd reduced hepatic GSH content with a concomitant reduction in GSH-Px. At higher doses of Hpd and light, there was a significant reduction in hepatic vitamin A levels. Combination of Hpd and light in all doses reduced vitamin E content in liver. The decreased biological antioxidant contents and GSH-Px may be attributed to their utilization for the scavenging of free radicals generated by Hpd and light in tissues. However, no change in catalase activity and vitamin C content in liver was noted in experimental rats. The results suggest that exposure to higher doses of Hpd with light alters oxidant stress system and TBARS content in rat.

Effect of increased level of CO2 exposure in a closed environment on calcium and phosphorus balance in rats.

In rats, exposed to increased ambient CO2 level (1.5%) for 30 days a 40% reduction in food intake during first 10 days was observed which subsequently improved. Similarly the body weight also declined initially, which showed progressive gain thereafter, almost reaching that of ad libitum fed control by 30th day. The lowered Ca intake consequent to reduced food consumption was followed by diminution in renal and faecal excretion of Ca. The lowered renal Ca excretion was probably unrelated to reduced Ca intake, since the pair-fed-control, not exposed to raised CO2 level, did not show any such alteration. The net result was a drastic reduction in Ca balance despite the diminution in its excretion. Though the intake and renal excretion of P were reduced in the CO2 exposed group due to a reduction in food intake, the P balance showed a cyclic pattern as in the pair-fed controls. The serum Ca after 30 days' exposure remained unchanged while the serum inorganic P showed a variation. The data indicated that hypercapnia produced hypophagia which affected growth of rats. The reduced renal excretion of Ca may not pose a risk on calcification of soft tissues, since its retention was also reduced on exposure to raised concentration of CO2.