Reversal of net secretion to net absorption of potassium in rat large intestine by dietary potassium depletion

Feeding rats a diet low in potassium and high in sodium for 2 weeks led to a reversal of net potassium secretion to net potassium absorption in ligated segments of distal large intestine (colon descendens and rectum) under in-vivo conditions. This change in the direction of net potassium transport is probably important for the maintenance of potassium homeostasis.     

Reversal of net secretion to net absorption of potassium in rat large intestine by dietary potassium depletion

Summary Feeding rats a diet low in potassium and high in sodium for 2 weeks led to a reversal of net potassium secretion to net potassium absorption in ligated segments of distal large intestine (colon descendens and rectum) under in-vivo conditions. This change in the direction of net potassium transport is probably important for the maintenance of potassium homeostasis.The technical assistance of Mrs U. Seeliger is gratefully acknowledged.     

The diet and gut microflora influence the distribution of enteroendocrine cells in the rat intestine

Several functions of the gut are locally influenced by peptides and biogenic amines released from enteroendocrine cells. The aim of the present study was to assess whether the luminal stimulus of diet or microbial flora or diet-microbial interactions have an influence on the distribution of enteroendocrine cells along the crypt-surface axes of the small and large intestine. The effects of diet and indigenous flora were investigated by comparing the numbers of argyrophil and serotonin immunoreactive cells in the jejunum and colon of germ free and conventional rats fed either a purified diet containing fine ingredients or a commercial diet containing crude fibre of cereal origin. The effects of human flora were analysed in germ-free rats inoculated with human faecal organisms. 1. Feeding the commercial diet reduced the number of argyrophil endocrine cells in the jejunum and serotonin immunoreactive cells in the colon of gern-free animals but increased the serotonin immunoreactive cells in the colon of conventional animals. 2. The rat flora increased the serotonin immunoreactive cells in the colon of animals fed a commercial diet and decreased in those fed a purified diet. 3. Inculation of human flora increased the numbers of serotonin immunoreactive cells both in the jejunum and colon. The results provide evidence that the dietary changes and diet-microbial interactions can affect the regional number of enteroendocrine cells.     

Lack of effect of butylated hydroxytoluene on dimethylhydrazine-induced colon carcinogenesis in rats.

Rats were given 6600 ppm of butylated hydroxytoluene (BHT) in the diet along with 10 weekly oral doses of dimethylhydrazine (DMH, 30 MG/KG). The incidence and mean number of colonic tumors produced were similar to that of rats given DMH alone. Thus, BHT did not provide any protective effect against colon carcinogenesis.     

Experimental liver fibrosis induced in rats receiving high doses of alcohol and alternating between regular and vitamin-depleted diets

Liver fibrosis was induced in rats by simulating human alcoholic eating and drinking patterns. Alcohol addiction was established by gradually increasing the ethanol concentration in the drinking water; salts were added at the terminal stage. The hepatocytes of rats receiving alcohol concentrations exceeding 50% (v/v) (similar to vodka) exhibited alcoholic hyaline (Mallory bodies). Alcoholic liver fibrosis was induced by alternating between regular and autoclaved (vitamin-depleted) diets, simulating the irregular eating habits of human alcoholics. In the livers of rats receiving 70% (v/v) ethanol (comparable to absinthe) with 25% saline and fed the alternating diets, pericellular fibrosis was induced. No significant difference in calorie intake between control and alcohol rats was detected except when rats underwent drinking bouts (heavy drinking phase). This indicates that neither a high-fat diet nor a choline-depleted diet is necessary to induce the alcoholic fibrosis seen in human alcoholics.     

Radiostrontium-Ausscheidung im Kot junger Ratten nach calciumreicher Ernährung

Summary Young immature rats of both sexes were fed with a diet either high (1.95%) or low (0.31%) in Ca content. A s.c. injection of weightless⁹⁰Sr results in a better excretion of radiostrontium with the faeces during feeding with high Ca diet. The retention of activity in the femori 30 days after injection is, in the same case, lower than by feeding with low Ca diet.     

Ovarian stimulation by exogenous gonadotrophins in fetal ethanol-exposed immature rats

Adult pregnant rats were given either an ad libitum liquid diet containing 5% ethanol, a pair fed liquid diet or an ad libitum diet of rat chow and water administered throughout pregnancy and during the nursing period. The female offspring received either pregnant mare's serum gonadotrophin (PMSG) or PMSG followed by human chorionic gonadotrophin (hCG) at 30 days of age. The ovaries of fetal ethanol-exposed animals responded greater to the exogenous gonadotrophins with enhanced ovarian weights, increased numbers of ova shed, greater numbers of corpora lutea and antral follicles, and higher serum progesterone levels than in animals exposed to the control diets during gestation.     

Ovarian stimulation by exogenous gonadotrophins in fetal ethanol-exposed immature rats

Summary Adult pregnant rats were given either an ad libitum liquid diet containing 5% ethanol, a pair fed liquid diet or an ad libitum diet of rat chow and water administered throughout pregnancy and during the nursing period. The female offspring received either pregnant mare's serum gonadotrophin (PMSG) or PMSG followed by human chorionic gonadotrophin (hCG) at 30 days of age. The ovaries of fetal ethanol-exposed animals responded greater to the exogeneous gonadotrophins with enhanced ovarian weights, increased numbers of ova shed, greater numbers of corpora lutea and antral follicles, and higher serum progesterone levels than in animals exposed to the control diets during gestation.     

Renal effects of a high unsaturated fat diet in renal artery stenosis in rats

The renal effects of an unsaturated fat (UNSAT) diet in mild to moderate two-kidney, one-clip (2K1C) renovascular hypertension were evaluated. An UNSAT diet (37% by energy) prevented the development of hypertension compared to 2K1C rats fed a high saturated fat (SAT) (37% by energy) and a normal fat (CONTROL) (11% by energy) diet. Urinary sodium and fractional sodium excretion increased in 2K1C rats as compared to SHAM operated controls, regardless of the diet received. In the early weeks of the experiment (weeks 2–4 post-surgery to induce hypertension), an enhanced natriuresis occurred in the 2K1C UNSAT as compared to the 2K1C CONTROL and SAT diet groups. This resulted from an increase in the glomerular filtration rate (GFR in mls·min^–1) as measured using the single-injection [⁵¹Cr] EDTA method (2K1C UNSAT; 1.99±0.18 versus 2K1C SAT; 1.27±0.09, p<0.02; and versus SHAM CONTROL; 1.45×0.01; p<0.02). The increased GFR was not associated with alterations in effective renal plasma flow (ERPF) as measured using the single-injection [¹²⁵I] Na hippurate method. No differences in sodium excretion; GFR; ERPF or renal blood flow (microsphere technique) were noted between the 2K1C UNSAT and SAT diet groups at weeks 6–8 post-surgery, despite a continued antihypertensive effect of the UNSAT diet. Hence, the antihypertensive effect of an unsaturated fat diet in 2K1C renovascular hypertension in rats is associated with transient glomerular changes leading to an enhanced natriuresis.     

Maternal influences on cardiovascular pathophysiology.

Elevated blood pressure (BP) is of special clinical significance because of its association with pathophysiologies such as heart disease, renal failure, and stroke. We described the development of a protocol for use with hypertensive rats in which prepubertal exposure to a high salt (8% NaCl) diet results in a pathophysiological syndrome including rapid increase in BP, failure to maintain normal weight gain, renal damage, cerebrovascular lesions, and early mortality. These phenomena are described for the inbred spontaneously hypertensive rat (SHR), and for reciprocal F1 hybrids of a cross between SHR and the Dahl salt-sensitive (SS/Jr) inbred strain. The study with reciprocal F1s revealed striking effects of maternal environment on pathophysiological response to a high salt diet. F1s nurtured by SHR mothers weighed less at 35 days of age, and after exposure to the high salt diet suffered more rapid BP increases, greater incidence of stroke, body weight loss, and mortality, than F1s nurtured by SS/Jr dams. These results suggest that maternal mediation of the nutritional status of the animal may play an important role in determining susceptibility to elevated BP and subsequent pathophysiology associated with exposure to a high salt diet. The implication of these findings for human hypertension is briefly discussed.     

Colon absorption of water and NaCl in the rat during lactation and the possible involvement of prolactin

Summary The absorption of water and NaCl by the ascending colon of female rats was significantly increased by prolactin treatment in virgin rats and during suckled lactation. Bromocriptine treatment of lactating rats resulted in decreased colonic absorption, suggesting that increased prolactin secretion may be responsible for the enhanced colonic absorption seen during lactation.This study was aided by NIH/Fogarty Fellowship F 05 TWO 2738 and by NSF Grant PCM-78-10348 to Professor H.A. Bern.The author is greatly indebted to Professor H. A. Bern for his support and helpful suggestions. Ovine prolactin was generously provided by NIAMDD. Professor E. Flückiger, Sandoz Ltd., kindly provided the bromocriptine used in this study. The assistance of William J. Young in taking care of the animals is greatly appreciated.     

Certain biochemical effects of garlic oil on rats maintained on high fat-high cholesterol diet

The feeding of a high fat-high cholesterol (HF-HC) diet to normal rats for 1 month increased the lipid components cholesterol and triglyceride in serum, liver and kidneys and decreased the serum albumin very significantly. Administration of garlic oil (100 mg/kg b. wt/day) for 1 month together with the HF-HC diet to another group almost nullified the lipid-increasing and albumin-decreasing effects of that diet. The reduction in total lipids, cholesterol and triglycerides and the restoration to normal level of serum albumin were highly significant in the garlic oil group. Adipose tissue triglyceride lipase activity was significantly increased in both the above groups with a much greater rise in the oil group.     

Certain biochemical effects of garlic oil on rats maintained on high fat-high cholesterol diet

Summary The feeding of a high fat-high cholesterol (HF-HC) diet to normal rats for 1 month increased the lipid components cholesterol and triglyceride in serum, liver and kidneys and decreased the serum albumin very significantly. Administration of garlic oil (100 mg/kg b. wt/day) for 1 month together with the HF-HC diet to another group almost nullified the lipid-increasing and albumin-decreasing effects of that diet. The reduction in total lipids, cholesterol and triglycerides and the restoration to normal level of serum albumin were highly significant in the garlic oil group. Adipose tissue triglyceride lipase activity was significantly increased in both the above groups with a much greater rise in the oil group.     

Plasma lipid concentration and lipoprotein distribution in exercising and nonexercising rats fed a high sucrose diet

Summary Voluntary physical activity in rats fed a high sucrose diet reduces the plasma triglyceride level but has no major influence on the lipoprotein distribution.Acknowledgment. The excellent technical assistance of Ida Goffeng Bay is gratefully acknowledged.     

Hypolipidemic effects of garlic oil in rats fed ethanol and a high lipid diet

Summary Feeding of ethanol and a high fat-high cholesterol diet to rats markedly increased the total lipids in the liver, and cholesterol and triglyceride levels in the serum, liver and kidneys. However, when ethanol mixed with 0.5% garlic oil was fed to animals maintained on the high fat-high cholesterol diet, these lipid levels were significantly reduced to levels near to those seen in untreated control rats. Garlic oil did not reduce the serum albumin or the total proteins of liver, kidneys or serum when fed along with ethanol. Probably the garlic oil enhances the catabolism of dietary cholesterol and fatty acids.The authors acknowledge with thanks the financial assistance of the University of Maiduguri for carrying out this project.     

Maternal influences on cardiovascular pathophysiology

Elevated blood pressure (BP) is of special clinical significance because of its association with pathophysiologies such as heart disease, renal failure, and stroke. We described the development of a protocol for use with hypertensive rats in which prepubertal exposure to a high salt (8% NaCl) diet results in a pathophysiological syndrome including rapid increase in BP, failure to maintain normal weight gain, renal damage, cerebrovascular lesions, and early mortality. These phenomena are described for the inbred spontaneously hypertensive rat (SHR), and for reciprocal F₁ hybrids of a cross between SHR and the Dahl salt-sensitive (SS/Jr) inbred strain. The study with reciprocal F₁s revealed striking effects of maternal environment on pathophysiological response to a high salt diet. F₁s nurtured by SHR mothers weighed less at 35 days of age, and after exposure to the high salt diet suffered more rapid BP increases, greater incidence of stroke, body weight loss, and mortality, than F₁s nurtured by SS/Jr dams. These results suggest that maternal mediation of the nutritional status of the animal may play an important role in determining susceptibility to elevated BP and subsequent pathophysiology associated with exposure to a high salt diet. The implication of these findings for human hypertension is briefly discussed.     

Peptide YY enhances NaCl and water absorption in the rat colon in vivo.

Peptide YY (PYY) is thought to possess paracrine and endocrine functions. The highest concentrations of this peptide are in the colonic mucosa. The effect of PYY on electrolyte and water transport in the rat colon was studied in vivo. Under urethane anesthesia, rat colonic loops were perfused at a constant rate with physiological buffer solution containing phenol red as a nonabsorbable volume marker, and net movements of water, sodium, chloride and potassium in the perfused colon were determined every 10 min. Intravenous administration of PYY produced a dose-dependent increase in the net absorption of sodium chloride and water, as well as a decrease in the net secretion of potassium. PYY inhibited the reduction in net absorption of sodium chloride and water evoked by vasoactive intestinal peptide (VIP), but did not affect the VIP-evoked increase in net potassium secretion. These findings suggest that PYY acts as an enhancer of sodium chloride and water absorption and as an antagonist to VIP-induced secretion in the colon.     

Peptide YY enhances NaCl and water absorption in the rat colon in vivo

Peptide YY (PYY) is thought to possess paracrine and endocrine functions. The highest concentrations of this peptide are in the colonic mucosa. The effect of PYY on electrolyte and water transport in the rat colon was studied in vivo. Under urethane anesthesia, rat colonic loops were perfused at a constant rate with physiological buffer solution containing phenol red as a nonabsorbable volume marker, and net movements of water, sodium, chloride and potassium in the perfused colon were determined every 10 min. Intravenous administration of PYY produced a dose-dependent increase in the net absorption of sodium chloride and water, as well as a decrease in the net secretion of potassium. PYY inhibited the reduction in net absorption of sodium chloride and water evoked by vasoactive intestinal peptide (VIP), but did not affect the VIP-evoked increase in net potassium secretion.These findings suggest that PYY acts as an enhancer of sodium chloride and water absorption and as an antagonist to VIP-induced secretion in the colon.     

Hepatic phosphatidylcholine synthesis in deficiency of lysine and threonine: effect of malathion

Rats fed on a rice diet deficient in lysine and threonine showed increased activities of CDP-Choline pathway enzymes and incorporation of (methyl-3H)-choline into hepatic microsomal phosphatidylcholine, compared to rats fed on the same diet supplemented with lysine and threonine. However, the amount of microsomal phosphatidylcholine was significantly decreased in rats fed a deficient rice diet. These results suggest an enhanced phosphatidylcholine catabolism in rats fed on a rice diet deficient in lysine and threonine. Malathion administration reduced the amount of phosphatidylcholine in all the groups.     

Hepatic phosphatidylcholine synthesis in deficiency of lysine and threonine: effect of malathion

Summary Rats fed on a rice diet deficient in lysine and threonine showed increased activities of CDP-Choline pathway enzymes and incorporation of (methyl-³H)-choline into hepatic microsomal phosphatidylcholine, compared to rats fed on the same diet supplemented with lysine and threonine. However, the amount of microsomal phosphatidylcholine was significantly decreased in rats fed a deficient rice diet. These results suggest an enhanced phosphatidylcholine catabolism in rats fed on a rice diet deficient in lysine and threonine. Malathion administration reduced the amount of phosphatidylcholine in all the groups.