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Biomedical subjects

K Kitani

Publications and source records attributed to K Kitani.

244 records · Page 14Linked to original sources
PubMedDate not supplied

The effect of age on the biliary transport maximum (Tm) of bile salts in rats.

Age-related differences in the biliary transport maxima (Tm) values for taurocholate (TC) and tauroursodeoxycholate (TUDC) were examined in female Fischer-344 rats as well as Wistar-derived rats of both sexes. The Tm values for TUDC were more than two times higher than corresponding values for TC in young (3-month-old) rats of both sexes. Tm values for both bile salts tended to decline with age, demonstrating a significant negative correlation between the Tm (micromol/min per g liver) and rat age (months) for all rat groups. The decline in Tm value was, however, dominant in the first year with little significant change after 1 year. The results in the present study coupled with our previous observations for Tm values of sulfobromophthalein (BSP) and conjugated BSP support our hypothesis that the transport capacity for bile canalicular membrane generally declines with age in rats.

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Manifestations of experimental acute pancreatitis in young and old rats.

Two kinds of experimental pancreatitis were induced in young (4-6 month) and old (25-27 month) female Wistar rats: acute edematous pancreatitis was induced by intraperitoneal administration of a high dose of cerulein (40 micro/kg x 2) and acute hemorrhagic pancreatitis was intraductal injection of 1% deoxycholic acid. After these treatments, the plasma amylase concentration and pancreatic wet weight were determined and the pancreas was examined histologically. In the groups with cerulein induced pancreatitis one of eight old rats died, whereas all five young rats survived. There was no specific finding macroscopically in the liver, kidney, lung or heart of old rats at autopsy after cerulein injection. The plasma amylase concentration and the pancreatic wet weight were significantly increased by administration of cerulein or deoxycholic acid in both young and old rats. There was no significant difference in the plasma amylase concentrations in young and old rats after the induction of acute pancreatitis. The increase in pancreatic wet weight was less in old rats than in young ones after deoxycholic acid treatment, but similar in the two groups after cerulein injection. The extents of histological changes were also similar in young and old rats. Thus, no evidence that aging increases susceptibility to pancreatitis was obtained.

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PubMedDate not supplied

Aging and the liver: functional aspects.

The drastic decline in the function of the hepatic microsomal cytochrome monooxygenase system, initially reported in male rat livers, was shown to be due to a feminization of male rat livers with aging. In female rat livers as well as in mouse livers, this system was found to stay unchanged with age. Phase II reactions which showed some decline with aging in male rat livers again stayed fairly stable with age in female rat and mouse livers. Glutathione S-transferase (GST) enzyme activities, which are very stable with age in female rat and mouse livers, demonstrated highly age-dependent changes when dietary conditions were manipulated, suggesting a potential age difference in the homeostatic regulation of this enzyme system. Using the fluorescence recovery after photobleaching (FRAP) technique, unique studies revealed an age-dependent decline in the lateral mobility of proteins in hepatocyte surface membranes. The protease inhibitor model of aging, initially proposed by Ivy for brain cells, has been validated in hepatocytes, demonstrating an accumulation of lipofuscin-like granules in young animals treated with i.p. infusion of leupeptin for only 2 weeks. Antioxidant enzyme activities such as superoxide dismutase (SOD) and catalase (CAT) in the liver were clearly demonstrated no to be reduced in general terms with aging. Rather, a clear increase in CAT enzyme activities with age was demonstrated in female rat livers, thus challenging the concept that intracellular enzyme activities generally decline with aging. In this paper, studies performed in Japan on aging and the liver over the past 30 years, with a focus on its functional aspects, are critically reviewed in terms of the clinical implications of these studies as well as on theories of aging in general.

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Age-dependence of the lateral mobility of lipids in hepatocyte plasma membrane of male rats and the effect of life-long dietary restriction.

The lateral diffusion constant of lipids (D(1)) in hepatocyte plasma membranes was measured in liver smears by means of the fluorescence recovery after photobleaching (FRAP) method, applying the label, N-4-nitrobenzo-2-oxa-1,3-diazolyl phosphatidylethanolamine (NBD-PE). Nineteen ad libitum fed, male Fischer-344 rats in four age groups (2.1-29.8 months of age) were studied. A highly significant negative linear age-correlation of D(1) (cc = 0.958) was found. D(1) values were 1.39 x 10(-9) cm2/s in the young rats, and only 6.77 x 10(-10) cm2/s in the oldest rats. Lipid lateral mobility is changing in parallel with that of proteins, having been measured previously also with the FRAP method by the authors. Fractional recovery values (FR%) of the lipids were lower than those of proteins even in the young ages, but also decreased linearly with age, therefore, the parameter, D, x FR decreased even steeper with age than D(1) itself. D(1) was also measured in a group of six male Fischer 344 rats having been kept on dietary restriction (DR) since their age of 1 month until 30 months of age (applying the every-other-day (EOD) feeding). DR caused an increase of D(1), compared with the age-matched ad libitum fed animals: the mean was 9.24 x 10(-10) cm(2)/s. FR% and D(I), x FR again increased considerably under DR. The results are interpreted in terms of the increased protein and lipid turnover under DR.

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PubMedDate not supplied

Increased biliary excretion of ouabain induced by bucolome in the rat.

1. Following the intravenous injection of 3H-ouabain (0.4 or 0.6 mg/100 g body weight) the plasma concentration and biliary excretion of ouabain were compared for control male Wistar rats and rats given bucolome (BC, 1-cyclohexyl-5-n-butyl-2,4,6-trioxoperhydroxypyrimidine, 20 mg/100 g) 40 min before the ouabain injection. In bucolome treated rats, the bile flow rate was 80-90% higher than in control rats and the biliary excretion rate of ouabain for the 40 min post-injection period was significantly higher in bucolome treated rat groups. The increase was due to an approximately two-fold increase in the excretion rate in the first 10 min period. On the other hand, plasma concentration of ouabain was significantly higher in bucolome treated rats compared with control rats at corresponding time intervals. Plasma volume as determined by 131I-labelled albumin dilution was not decreased in bucolome treated rats. 2. The results indicated that the significant increase in biliary excretion of ouabain administration was due to the enhancement of the hepatic transport and/or biliary excretion process and not due to an increase in hepatic uptake.

Animals↗
PubMedDate not supplied

Comparison of the effects of various anticholinergic drugs on human isolated urinary bladder.

We investigated the effects of various anticholinergic drugs (atropine, oxybutynin, terodiline and propiverine) on the contractions induced by acetylcholine, KCl, CaCl2, and electrical field stimulation, in human isolated urinary bladder smooth muscles using the muscle bath technique. Urinary bladders were obtained from 20 patients who underwent total cystectomy due to malignant bladder tumor. The detrusor preparations were taken from the intact part of the dome of the bladder. Acetylcholine caused a concentration-dependent contraction in human detrusor preparations. Atropine (10(-9)-10(-6) M), oxybutynin (10(-8)-10(-5) M), terodiline (10(-7)-10(-5) M) and propiverine (10(-7)-10(-5) M) caused parallel shifts to the right of the concentration-response curves to acetylcholine. The rank order of pA2 values was: atropine > oxybutynin > terodiline = propiverine. Atropine did not suppress the maximum contraction to acetylcholine, while the other drugs significantly suppressed the maximum contractions at the higher concentrations. Each drug caused a concentration-dependent inhibition of the KCl (80 mM)- and CaCl2 (5 mM)-induced contractions; the maximum inhibitions of terodiline and propiverine were significantly greater than those of oxybutynin and atropine. Each drug caused a concentration-dependent inhibition of the contraction induced by electrical field stimulation; the maximum inhibitions of terodiline and propiverine were significantly greater than those of oxybutynin and atropine. The results suggest that the drugs have both anticholinergic and calcium antagonistic effects. Furthermore, it also appears that part of the human bladder contraction, which was significantly inhibited by terodiline and propiverine, is an atropine-resistant component.

Acetylcholine↗