The composition of the renal papilla, medulla and cortex was studied in rats during hydropenia and water diuresis, and a few observations were made on hamsters.In confirmation of earlier findings, osmolality increased progressively from the outer medulla towards the tip of the papilla in hydropenia; this osmolal gradient was due largely to increasing concentration and content of sodium and urea. The osmolality at the tip was close to that of simultaneously collected urine. In water diuresis, this osmolal gradient was smaller but still present.Ammonium content and concentration increased progressively from the outer medulla towards the papilla.In water diuresis, the concentration and content of urea fell, but the gradient was still present. Sodium was little altered, and the fall in ammonium content, though considerable, contributed little to the total osmolal change.Potassium concentration and content were high in the terminal segment in diuresis and antidiuresis, and in water diuresis exceeded the hydropenic value.The water content increased progressively from the outer towards the inner medulla, but at the tip it was lower than in the adjacent segment. This distribution was qualitatively similar in both conditions, but the absolute level was higher in all medullary segments in water diuresis.The results are discussed in relation to the mechanism of production and maintenance of medullary hypertonicity. O'Dell, 1959, sheep, 1961, beaver, rabbits and psammomys; Eigler et al., 1962, rats; Levitin et al., 1962, dogs] have revealed that the sodium and urea concentration rises progressively from the cortico-medullary junction towards the medulla and papilla. It is clear from chemical, cryoscopic [Wirz et al., 1951; a] and direct micropuncture [Wirz, 1953[Wirz, , 1957Gottschalk and Mylle, 1959;Gottschalk, 1961;Lassiter et al., 1961] studies that in hydropenia the osmolality of medullary interstitial fluid rises progressively from the cortico-medullary junction towards the medulla and papilla.Observations during water diuresis are fewer. The medulla is still hypertonic to plasma in dogs [Ullrich et al., 1955;Ullrich and Jarausch, 1956;Levitin et al., 1962], and in rats , but the mechanism involved in establishing the differences between hydropenia and water diuresis is poorly understood.In an attempt to elucidate the mechanism involved, the chemical composition of cortex, medulla and papilla of rats and hamsters was analyzed during hydropenia and water diuresis. In particular, the relative contributions of sodium and urea, and the variation in water content, were studied.

Rats in water diuresis were given intravenous injections of vasopressin, or of isotonic NaCl for controls. Serial urine sampling showed that maximal osmolality and minimal flow were achieved half an hour after vasopressin injection, and that urea excretion was low at this time. In animals killed half an hour after injection, the composition of the renal papilla, medulla and cortex was studied.The urea and ammonium concentration and content increased in the inner medulla after vasopressin injection, and the water content increased in all the kidney slices, but significantly so only in the papilla. The medullary osmolality did not alter appreciably, the accumulation of urea and ammonium being counterbalanced by the increase of water. The urine osmolality did not reach the level found in the medulla. No appreciable change of sodium or potassium concentration or content of kidney slices was observed after vasopressin injection. The results are discussed in relation to means whereby vasopressin induces antidiuresis and urinary hypertonicity.IN the preceding paper [Saikia, 1965], the differences between the composition of the renal medulla in hydropenic and water diuretic rats were studied. It is commonly supposed that these differences are due to the presence or absence of vasopressin. The present paper attempts to discover how far this is true, that is, how far the condition in water diuresis can be altered rapidly to that of hydropenia by an injection of vasopressin.Some workers studying this problem have used very large doses of vasopressin [Jaenike, 1961;Levitin et al., 1962], though Perlmutt [1962] has used a dose nearer the likely physiological range, as has been here attempted. METHODSWater diuresis was produced in hydrated rats by the methods described in the previous paper [Saikia, 1965].Two and a half hours after water injection, when the diuresis was maximal and steady, thirteen rats were given Lysine-vasopressin (Sandoz; 04 mu per 100 g. body weight in isotonic saline) by single intravenous injection into the tail vein, and thirteen had only isotonic saline to serve as control.Urine was collected at the time of injection, and in ten rats of each group half an hour later, immediately before removal of kidneys. Residual urine in the bladder was measured.In three rats of each group, micturition was induced, by brief ether inhalation, at 15 min. intervals after injection for 1 hr. The kidneys were not removed in these

Blood group distribution ofABO and Rh factor were studied among 322 Nepalese(male - 178; female - 144) and 100 Indians (male - 72; female - 28;) in a group ofmedical students.The percentage of different groups A, B, AB and 0 in Nepalese showed relativelymore in A & AB and less in 0 groups than Indians. The Rh (-)ve was more amongIndians (9%) than Nepalese (1.5%).This difference is likely to be due to difference of ethnic origin of Indian & Nepalese.The population of Nepal is a mixture ofTibeto-Burman, Australoid and Indo-Aryanraces.Key Words: A, B, O, Rh blood group.