Effect of histamine on technetium-99m excretion by gastric mucosa

The ability of histamine to increase excretion of 99mtechnetium by gastric mucosa was investigated in dogs with Heidenhain pouches and denervated antral pouches. Histamine increased Heidenhain pouch 99mtechnetium output in a dose-related manner, and 99mtechnetium output was related linearly to acid output. Antral pouch 99mtechnetium output was unchanged by increasing doses of histamine. The study suggests that concomitant use of histamine may improve the accuracy of 99mtechnetium scanning in the clinical diagnosis of conditions caused by ectopic gastric mucosa.     

Intestinal ascorbic acid transport following diets of high or low ascorbic acid content

Active transport of ascorbic acid in ileum is mediated by a carrier mechanism at the brush border membrane. This mechanism may show compensatory changes in activity in response to alterations of dietary ascorbic acid content. The unidirectional influx of ascorbic acid across the brush border into epithelial cells of guinea pig ileum was determined in vitro. Influx was significantly reduced in scorbutic animals and following 14 or 28 days of high doses (5 or 25 times normal) of ascorbic acid. The transport rate was reduced by intramuscular administration of ascorbic acid, suggesting that the transport mechanism may respond to circulating levels of the vitamin.     

Influence of chronic undernutrition on oxygen consumption of rats during exercise

The current study was undertaken to examine the effects of dithiothreitol (DDT), a sulfhydryl-reducing agent and heavy metal chelator, on the course of heavy metal-induced acute renal failure in the rat. Groups of rats in metabolic cages received uranyl nitrate (UN) alone, UN plus DTT, mercuric chloride (HgCl2) alone, and HgCl2 plus DTT. UN injected alone produced azotemia, decreased creatinine clearance, and rising fractional sodium excretion over the 48 hr of study. These effects of UN on renal function were not observed when DTT was administered 30 min after UN injection. Qualitatively similar results were obtained with HgCl2-induced acute renal failure. Groups of rats were killed at 6 hr after UN plus DTT, HgCl2 alone, or HgCl2 plus DTT; and determinations of plasma renin activity (PRA) and renin activities of the superficial and deep juxtaglomerular apparatus (JGA) were performed. PRA's and JGA renins were increased in animals receiving either UN or HgCl2 alone, but not in the rats receiving both DTT and UN or HgCl2. The effect of DTT on distribution of 203Hg was also examined. Treatment with DTT did not alter the renal accumulation of 203Hg, suggesting that this agent does not act by limiting renal exposure to the heavy metals. Thus, DTT ameliorates the course of heavy metal-induced ARF, and this effect is associated with prevention of heavy metal-induced alterations in sodium excretion and renin-angiotensin system activity.