Urea recycling in active golden-mantled ground squirrels (Spermophilus lateralis).

In response to fasting or fasting combined with water deprivation urine urea excretion declined sharply in normothermic ground squirrels (Spermophilus lateralis) when compared with laboratory rats. Intraperitoneal injection of urea equivalent to 0.3% of body weight failed to increase blood urea in 12-h fasted ground squirrels, and led to little urine urea excretion when compared with similarly treated rats. Collection of expired CO2 from fasted or fasted water-deprived ground squirrels that were urea loaded and injected with a tracer dose of 14C-tagged urea revealed a 1,000- to 1,500-fold greater 14CO2 expiration than controls. Treatment of fasted squirrels with antibiotics (penicillin, tetracycline, or sulfamethazine) to reduce intestinal microflora reduced expired 14CO2 to control levels. In fasted squirrels, drug treatment also enhanced urine urea excretion with values approaching those of controls. The results of these experiments point to the possibility of urea nitrogen recycling in nutritionally stressed ground squirrels.

Direct immunochemical detection of prostaglandin-E and cyclic nucleotides in human malignant tumors.

Immunofluorescent localization of prostaglandin-E (PGE), cyclic AMP (CAMP), and cyclic GMP (cGMP) was studied in tumor tissues from 40 patients with a variety of solid tumors. Representative normal tissues served as controls. Rabbit antisera specific for PGE or the cyclic nucleotides were used, and the reactions observed were correlated with the degree and type of lymphocytic reaction at the tumor margins. Strong PGE immunofluorescence was detected in tumor cells in 27 of 42 malignancies; by contrast nine of 13 normal tissues showed weak PGE reactions, cAMP was detected in 30 of the 42 malignancies; cGMP was noted in only seven of the 42 malignant tissues and in none of the normal tissues studied. The most common malignant tumor profile (17/42) was that of positive PGE and cAMP and negative cGMP staining. Tumors showing strong staining with anti-PGE or cAMP demonstrated a distinct trend towards heavier lymphocytic infiltration with a predominance of T cells at their margins, although this association did not reach statistical significance in the present material.

Effects of follicle-stimulating hormone and luteinizing hormone on ovarian cyclic AMP and prostaglandin E in vivo in rats treated with indomethacin.

The role of prostaglandins in both FSH- and LH-mediated increases in ovarian cyclic AMP was examined in rats in vivo. Dose-related increases in ovarian cyclic AMP levels were observed 10 min after intravenous injection of FSH or LH. No changes in ovarian prostaglandin E (PGE) content were detected after injection of either gonadotrophin at doses which substantially enhanced cyclic AMP accumulation. Prior treatment of rats with indomethacin produced a greater than 50% decrease in ovarian PGE levels, but did not prevent the FSH- or LH-induced rise in ovarian cyclic AMP concentration. These in vivo experiments do not support the concept that PGE plays a role as an obligatory mediator for the gonadotrophin-induced rise in ovarian cyclic AMP levels.