The insulin sensitivity of the diaphragm and parametrial adipose tissue in animals with ventromedial hypothalamic (VMH) lesions and controls were assayed in vivo by studying the intra‐peritoneal action of exogenous insulin. Lipogenesis and glycogen synthesis were stimulated to the same extent in lesioned and control animals. This implies that the co‐existence of hyper‐insulinemia and normoglycemia previously demonstrated in lesioned animals cannot be attributed to decreased insulin sensitivity. Increased gluconeogenesis in the lesioned animals is indicated by elevated levels of plasma urea. This may contribute to the maintainance of normoglycemia in the presence of hyperinsulinemia and normal insulin sensitivity. It is suggested that the profound metabolic effects of VMH destruction is caused by a disturbance in the nervous control of gastro‐intestinal functions. This may lead to alterations in the endocrine pancreatic secretion, and possibly also in liver metabolism.

The fluoride sensitivity of cells released from rat livers and kidneys by collagenase perfusion was investigated by measuring effect on protein synthesis rate in vitro. Both cell types were sensitive to fluoride with clear concentration/effect relationships. Significant difference in sensitivity for fluoride between the cell types was found, with the kidney cells being the most sensitive type.

Absrruct:The fluoride sensitivity, determined as effect on protein synthesis (incorporation of "C-leucine), of liver and kidney cells in suspension culture was explored. The cells were freshly prepared by collagenase perfusion from rats given drinking water with or without addition of 100 p.p.m. (5.26 mM) fluoride for 9-28 weeks. The fluoride sensitivity of the liver cells from rats given fluoridated water for more than 9 weeks was decreased compared to cells from control rats, whereas the fluoride sensitivity of the kidney cells from fluoride exposed and control rats appeared similar. Fluoride resistance (i.e. decreased sensitivity)may thus develop also in cells in vivo. When exposed to 3 mM NaF for 1 hour the intracellular concentration of fluoride in liver cells from fluoride exposed and control animals was similar.

Rats were exposed to fluoride (F) for up to 8 weeks through the drinking water containing 100 p.p.m. F. Urine samples were regularly collected, together with tissue samples of liver and kidney at termination. All samples were assayed for cyclic AMP. No F-effect was found on liver or kidney levels of cyclic AMP. In the urine from the F-exposed rats there was an overall increase in the cyclic AMP concentration, but a decreased or unaffected 24 hrs urinary excretion of cyclic AMP. However, the F-exposed rats exhibited a considerably lower diuresis than the control animals. Because a significant negative correlation was found between diuresis and urinary concentration of cyclic AMP, the material was corrected to similarity in the mean diuresis between the two groups. Then no effect of F-exposure could be detected either in the urinary concentration or the daily excretion of cyclic AMP.

Rats transplanted with medullary thyroid carcinoma (MTC) were divided into 3 groups which received for 34 weeks diets with low (0.09%), medium (0.40%) or high (1.80%) calcium content with a calcium/ phosphate ratio 2:1. After 6 weeks the different calcium regimens produced corresponding variations in serum calcium and inverse changes in serum magnesium. No alterations in serum proteins were observed.Serum immunoreactive calcitonin (iCT) was unaltered until week 28 of the experiment, but thereafter increased rapidly by about 4-fold. No difference in serum iCT was observed between the 3 groups at any time. Immunoreactive serum gastrin was reduced in rats on medium and low calcium diet compared to those on a high calcium diet. After 28 weeks, when serum iCT was rising, gastrin values fell in rats on high calcium diet to levels approaching those in the other groups. With increased serum iCT (weeks 28\p=n-\34) serum gastrin concentrations were low and equal in the 3 groups despite different serum calcium concentrations. Electronmicroscopic examination of tumours from the various diet groups did not reveal significant ultrastructural differences. In conclusion: low, medium and high calcium intake gave corresponding changes in serum calcium. Dietinduced hypercalcaemia was not normalized by elevated serum iCT. In contrast, serum immunoreactive gastrin maintained by high calcium diet was suppressed by hypercalcitoninaemia. Calcitonin (CT) is a polypeptide hormone pro¬ duced by the parafollicular cells (C-cells) of the mammalian thyroid gland and the ultimobranchial body of many non-mammalian vertebrates (Hirsch