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Biomedical subjects

K Matsuda

Publications and source records attributed to K Matsuda.

At least 505 records · Page 28Linked to original sources

Age-related changes in rates of basal secretion of immunoreactive vasoactive intestinal polypeptide and dopamine into pituitary stalk blood from the hypothalamus in anesthetized male rats.

Age-related changes in prolactin (PRL) in systemic blood plasma, and in secretions of hypothalamic vasoactive intestinal polypeptide (VIP), an important candidate for PRL-releasing factor, and dopamine, a PRL-inhibiting factor, into the pituitary stalk blood were investigated. The experiments were performed on male urethane-chloralose-anesthetized Wistar rats of three different ages, i.e., (1) adult rats 5-8 months old, (2) middle-aged rats 12-15 months old, and (3) aged rats 24-26 months old. The concentration of immunoreactive PRL (iPRL) in systemic blood plasma of the aged rats was significantly higher than that of the adult rats (p less than 0.01). The secretion rate of hypothalamic immunoreactive VIP (iVIP) into the pituitary stalk blood was unchanged during aging, while that of dopamine was markedly increased in the aged rats in comparison with the value in both adult and middle-aged rats (p less than 0.01). These results indicate that the basal secretion of hypothalamic VIP is well maintained, while that of hypothalamic dopamine is augmented in aged rats with hyperprolactinemia. It can be assumed that the increase in the pituitary PRL secretion is a primary event during aging in rats, and that a high circulating level of PRL may facilitate the hypothalamic dopamine secretion through the activation of a negative feedback system of the hormone.

Aging↗

Effect of vitamin B2 deficiency on rat liver dihydropyrimidine dehydrogenase activity.

Effect of vitamin B2 deficiency on rat liver dihydropyrimidine dehydrogenase was investigated. It was found that the purified enzyme contains 2 mol flavin per molecule, which consists of equal proportions of flavin-adenine dinucleotide (FAD) and riboflavin 5'-phosphate (FMN). When rats were fed on a vitamin B2-deficient diet for 5 weeks, dihydropyrimidine dehydrogenase activity in the liver was diminished, followed by a decrease in enzyme concentration. Moreover, the addition of exogenous FAD or FMN did not restore the activity. Thus endogenous flavin may regulate the enzyme half-life or synthesis. Lowering of dihydropyrimidine dehydrogenase activity in the livers of rats fed on a vitamin B2-deficient diet did not affect the uridine, uracil and sigma UMP (the sum of acid soluble uracil 5'-nucleotides) pool in liver.

Animals↗

[Protective effect of prostaglandin E2 on ethanol-induced injury of chief cells isolated from guinea pig].

The mechanism by which PGE2 directly protects individual gastric cells from ethanol-induced injury was studied by using isolated gastric chief cells from guinea pig. Ethanol dose-dependently caused chief cell injury which was estimated by the release of lactate dehydrogenase (LDH) from chief cells. Pretreatment of chief cells with PGE2 reduced the cell damage caused by ethanol in time- and dose-dependent manner. The pretreatment at 37 degrees C and pH 7.4 with PGE2 maximally reduced the cell damage. This protective effect was reduced when the pretreatment was performed at either acid or alkaline pH or at reduced temperature. PGE2 did not stimulate any increase in cytosolic free Ca2+ concentration and initial Ca2+ influx rate. On the other hand, PGE2 stimulated an increase of cAMP accumulation in chief cells. However, pretreatment of chief cells with secretion, VIP, dbcAMP or forskolin failed to reduce subsequent injury caused by ethanol. These results suggest that PGE2 may protect chief cells against ethanol-caused injury probably via PGE type receptors coupled to as yet unidentified signal in gastric chief cells.

Animals↗

Localization of 14C-nizatidine in the gastric wall of rats.

Nizatidine (N-[2-[[[2- [(dimethylamino)methyl]- 4-thiazolyl]methyl]thio]ethyl]-N'-methyl-2-nitro-1,1-ethenediamine , CAS 76963-41-2) has a selective and competitive antagonism against histamine H2-receptors. The localization of 14C-nizatidine to the parietal cells of gastric mucosa which is the effective site of nizatidine, was studied. After oral administration of 14C-nizatidine to rats, the radioactivity was rapidly distributed at higher levels in the gastric mucosa than in the plasma. The mucosal level of nizatidine at 6 h after administration was still 63.3 ng/g tissue, being similar to the effective plasma concentrations in dogs and man. Nizatidine was confirmed to be retained as an unchanged drug in the gastric mucosa, supporting the duration of pharmacological effects of nizatidine. The localization of the drug in gastric wall after intraduodenal administration was examined by means of microautoradiography. The radioactivity of 14C-nizatidine absorbed as the fine developed silver granules was widely localized into the parietal cells in the mucosal layer through the gastric wall at 30 min after administration. Also at 2 h after administration, when the suppression of gastric acid secretion was strongest, the silver granules were almost uniformly localized all over the gastric wall, but the localization was generally less dense than at 30 min.

Animals↗

Study on the metabolic fate of catena-(S)-[mu-[N alpha-(3- aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc]. 1st communication: absorption, distribution, metabolism and excretion after single administration to rats.

Studies on the absorption, distribution, metabolism and excretion of 14C-Z-103 and 65Zn-Z-103 (catena-(S)-[mu-[N alpha-(3- aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) were performed after oral administration to rats. After oral administration of 14C-Z-103 and 65Zn-Z-103, the blood concentrations of 14C-radioactivity were 30- to 40-fold higher than those of 65Zn-radioactivity. The 14C-radioactivity showed a dose-dependent increase of Cmax and AUC values in the dose range from 13.1 mg/kg to 100 mg/kg, and remained longer in the blood. In contrast, no dose-dependent increase of AUC was observed with 65Zn-radioactivity, suggesting saturation of absorption at doses more than 30 mg/kg of 65Zn-Z-103. The major route of excretion of 14C-radioactivity was by excretion into the expired air, amounting to 38.8% of the administered dose, while the urinary and fecal excretions were low values at 4.1% and 13.3%, respectively. The radioactivity remaining in the carcass accounted for 39.3% of the dose. On the other hand, in the case of 65Zn-radioactivity, 85.0% of the administered dose was excreted into the feces and 10.5% of the dose remained in the carcass. Both 14C- and 65Zn-radioactivities were distributed to the whole body, while 14C-radioactivity showed higher concentrations in the body, and was retained longer than the 65Zn-radioactivity. When the plasma and the liver and kidney homogenates, from rats received 14C-Z-103, were treated with trichloroacetic acid (TCA), the radioactivities in the TCA-insoluble fraction increased as a function of time. Following the treatment of the homogenates with protease, the radioactivities in the TCA-insoluble fraction decreased. In vitro study was showed that L-carnosine of 14C-Z-103 added to the homogenates of liver and small intestine was metabolized to L-histidine. The results suggest that the remaining radioactivities in tissues and organs caused the incorporation of the metabolites of 14C-Z-103 into endogenous high molecular substances.

Animals↗

Study on the metabolic fate of catena-(S)-[mu-[N alpha-(3- aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc]. 2nd communication: absorption, distribution, metabolism and excretion after repeated administration to rats.

After repeated administration of 14C-Z-103 (catena-(S)-[mu-[N alpha-(3- aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) to rats for 21 days, the accumulation of radioactivity in the blood and tissues was proportional to the number of doses given. Following treatment of the terminal blood, plasma, liver and kidney samples with trichloroacetic acid (TCA) or protease, the radioactivity in these tissues was demonstrated to be TCA-insoluble and solubilized by the protease treatment. Thus, the accumulation of radioactivity after repeated administration of 14C-Z-103 was considered to be due to the utilization of the metabolites of L-carnosine, the constituent of Z-103, into a protein. The cumulative ratios of radioactivity excreted into the urine, feces and expired air and the radioactivity remaining in the carcass after repeated administration of 14C-Z-103 for 21 days were similar to those values obtained after a single administration, suggesting that repeated administration did not influence the excretion profile of Z-103. During the period of repeated administration of non-radioactive Z-103 to rats for 21 days, the fecal content of zinc was higher than that in nontreated rats, whereas it returned to the control level at 48 h after the final administration. There was no significant difference in the urinary concentration of zinc between treated and non-treated animals during the period of repeated administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗

Study on the metabolic fate of catena-(S)-[mu-N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc]. 3rd communication: transfer into fetus and milk in rats.

Studies on the transfer into the fetus and the milk were performed after administration of 14C-Z-103 and 65Zn-Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]- zinc], CAS 107667-60-7) to rats. After oral administration of 14C-Z-103 to pregnant rats, the transfer of radioactivity to the fetus was studied by means of whole body autoradiography (ARG) and measurement of radioactivity in the fetus. The concentration of radioactivity in the fetus was approximately the same as those in the blood and the placenta of the maternal animal. The transfer of radioactivity into the milk was demonstrated after administration of 14C-Z-103 to lactating rats. Radioactivity in the fetus and milk are considered to be due to metabolites of L-carnosine of Z-103, such as amino acid or protein. The distribution of radioactivity in the fetus was also observed after administration of 65Zn-Z-103 to pregnant rats. However, after administration of non-radioactive Z-103 to pregnant rats, the zinc level in the fetus was found to be almost the same level as that in the fetus of the untreated rats. The transfer of radioactivity to the milk was studied after administration of 65Zn-Z-103 to the lactating rats, and it was seen that the concentration of radioactive zinc in the milk was much lower than the endogenous level of zinc in the milk at any of the time points investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Study on the metabolic fate of catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc]. 4th communication: disposition of zinc and amino acids in rats, dogs and monkeys.

The time course of the zinc plasma concentrations in rats, dogs and monkeys and the metabolic fate of L-carnosine were investigated after oral administration of Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7). There was no intradiurnal variation in the plasma concentrations of endogenous zinc in rats, dogs and monkeys. The plasma concentrations of endogenous zinc in dogs and monkeys were approximately the same as that in humans, whereas the plasma concentration of zinc in rats was 2.2-fold higher than that in man. After administration of Z-103 to non-fasted dogs at 100 mg/kg, the plasma concentration of zinc reached Cmax at 0.5 h after administration (1.7-fold higher than endogenous zinc level), while the plasma concentration was the lowest in comparison with other animal species. After administration to fasting rats at 50 mg/kg, the plasma concentration of zinc reached Cmax at 1 h after administration (2.5-fold higher than endogenous zinc level) and decreased thereafter, returning to the endogenous level at 8 h after administration. After oral administration to monkeys at 10 mg/kg and 50 mg/kg, the Cmax values were 4.1-fold and 6.8-fold higher than the endogenous level, respectively. The Tmax values were achieved at 4-6 h and 8 h after each administration, respectively, showing slower absorption in comparison with other animal species.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

Single dose toxicity study on catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc] in mice and rats.

The toxicity of Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) was evaluated in mice and rats after single administration. LD50 values in mice were 1269 mg/kg for males and 1331 mg/kg for females by the oral route, 220 mg/kg for males and 165 mg/kg for females by the intraperitoneal route, and 758 mg/kg for males and 874 mg/kg for females by the subcutaneous route. LD50 values in rats were 8441 mg/kg for males and 7375 mg/kg for females by the oral route, 405 mg/kg for males and 422 mg/kg for females by the intraperitoneal route and more than 5000 mg/kg for both sexes by the subcutaneous route. No sex differences were observed. A decrease in locomotor activity, ventral posture, crouching, hypothermia and respiratory depression were observed in both mice and rats as the main clinical signs. In addition to these changes, induration, swelling and crust formation were observed at the subcutaneous injection site.

Administration, Oral↗

Repeated dose toxicity studies on catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc] in rats.

Thirteen- and 52-week oral toxicity studies of Z-103 (catena-(S)-[mu- [N alpha-(3-aminopropionyl) histidinato (2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) were carried out in rats. In a 13-week repeated dose toxicity study (37.5, 75, 150, 300, 600 or 1200 mg/kg/d), deterioration of the general condition was observed at 300 mg/kg/d or more, a decrease in body weight gain at 600 mg/kg/d or more. Approximately 40% of the animals were found dead or sacrificed in a moribund state at 1200 mg/kg/d. Furthermore, in the 600 mg/kg group changes in urine volume, blood urea nitrogen and weight of kidneys were observed, suggesting that Z-103 may have had adverse effects on the kidney. No sex difference was noted. From these results the no-effect dose level was estimated to be 150 mg/kg/d under the conditions of this experiment. In a 52-week repeated dose toxicity study (18.75, 37.5, 75 or 150 mg/kg/d), proliferation of small duct and atrophy of acinar cells in the pancreas were observed in both sexes of the 150 mg/kg/d group. No other dose-related changes were observed throughout the administration period. Therefore, the no-effect dose level was estimated to be 75 mg/kg/d under this condition.

Animals↗

Reproductive and developmental toxicity studies on catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc].

To evaluate the effects of Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl) histidinato (2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) on the reproductive performance of male and female rats, the general toxicity of dams, and the development, physical growth and reproductive performance of the next generation, Z-103 was administered to rats prior to, and in the early stages of pregnancy, during the period of fetal organogenesis, and during the perinatal and lactation periods, and to rabbits during the period of fetal organogenesis at the appropriate doses for each study. At the administration of Z-103 prior to and in the early stages of pregnancy in rats, no dose-related abnormalities were observed in the reproductive performance of either sex. Furthermore, there were no death or evidence of teratogenicity or repressive effect on growth in fetuses. Administration of Z-103 during the period of fetal organogenesis in rats affected the growth of embryos and fetuses at 1200 mg/kg. At 600 mg/kg or less, however, there were no death, teratogenicity or repressive effect on growth in fetuses, and furthermore, no dose-related abnormalities were observed in growth, physical development, behavior and reproductive performance in offspring. Administration of Z-103 during the period of fetal organogenesis in rabbits caused a decrease in the number of live fetuses at 300 mg/kg suggesting that 300 mg/kg of Z-103 may have a lethal effect on fetuses. There were, however, neither teratogenicity nor any repressive effect on the growth of fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Drug-Induced↗

Antigenicity studies on catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc].

The antigenicity of Z-103 (catena-(S)-[mu[N alpha-(3-aminopropionyl) histidinato(2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) was evaluated using the following assay procedures: 1. active systemic anaphylaxis (ASA) in guinea pigs. 2. passive cutaneous anaphylaxis (PCA) in guinea pigs with serum from guinea pigs sensitized with Z-103, 3. delayed type skin reaction (Maximization Test) in guinea pigs, 4. passive cutaneous anaphylaxis (PCA) in rats with serum from mice sensitized with Z-103 and 5. passive hemagglutination (PHA) with serum from mice sensitized with Z-103. In each test except for Maximization Test, the sera obtained 1 or 6 h (hereinafter designated as 1-h-sera or 6-h-sera) after a single oral administration of 500 mg/kg of Z-103 to the unused rats, guinea pigs or rabbits, were used as the challenge antigen. 1. ASA in guinea pigs: No anaphylaxis reaction was observed in any of the sensitized guinea pigs by elicitation with challenge antigen. 2. PCA in guinea pigs: PCA titer of sera from all the sensitized animals was less than 1 in elicitation with the challenge antigen. 3. Delayed type skin reaction test: No skin reaction was observed in sensitized guinea pigs after intradermal injection or dermal application of Z-103. 4. PCA in rats: PCA titer of sera from BALB/c and C3H/He mice sensitized with Z-103 was less than 5 in elicitation with the challenge antigen. 5. PHA reaction: When erythrocytes coated with challenge antigen were added to sensitized sera, the hemagglutination titer was less than 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaphylaxis↗

Mutagenicity studies on catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau]-zinc].

Z-103 (catena-(S)-[mu-[N alpha-(3-aminopropionyl)histidinato (2-)-N1,N2,O:N tau]-zinc], CAS 107667-60-7) was examined in the bacterial mutation test, a chromosomal aberration test with mammalian cells in culture and the micronucleus test using male mice. 1. Z-103 did not increase the number of revertants in Escherichia coli WP2 uvrA when tested at up to 5000 micrograms/plate in the presence or absence of metabolic activation. And Z-103 did not increase mutants in Salmonella typhimurium SD 100 (streptomycin dependent strain) or in Salmonella typhimurium TM677 (8-azaguanine sensitive strain) when tested at up to 5000 micrograms/ml in the presence or absence of metabolic activation. 2. The chromosomal aberration test was carried out with cultured Chinese hamster lung cells (CHL). For the direct assay procedure, the cells were treated with 3.3 x 10(-4)-3.3 x 10(-6) mol/l Z-103 for 24 or 48 h, after which time chromosome preparations were made. For the metabolic activation assay procedure, the cells were treated with 1.0 x 10(-3)-3.3 x 10(-6) mol/l of Z-103 for 6 h in the presence or absence of metabolic activation, and the chromosome preparations were made after a further 18-h incubation in the absence of Z-103 and metabolic activation. Z-103 did not cause chromosome aberrations either in the presence or in the absence of metabolic activation. 3. The micronucleus test was performed in ddY male mice. Z-103 was administered orally to mice at a dose of 400, 200 or 100 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

The influence of experimentally produced oligohydramnios on lung growth and pulmonary surfactant content in fetal rabbits.

To study the effect of oligohydramnios on lung growth and biochemical lung development in fetal rabbits, amniotic fluid was drained through a tube inserted into the maternal peritoneal cavity on the 23 day of gestation. Littermate fetuses without an amniotic shunt were used as controls. The fetuses were delivered abdominally on the 28 day of gestation. In a total of 8 pregnant does, 17 fetuses underwent amniotic shunting and 22 fetuses were used as controls. The amniotic shunt produced a significant reduction in the amniotic fluid volume. There were no differences in the wet weights of the fetal body, liver or brain between the two groups. However, the amniotic shunt significantly decreased the wet weight of the fetal lung, fetal lung wet weight/body weight ratio, and protein concentration per lung as compared to the control fetuses. In the fetal liver and brain tissues, no changes were found in the concentrations of total phospholipids, phosphatidylcholine (PC) or disaturated phosphatidylcholine (DSPC, the main component of lung surfactant) per g of wet tissue and per mg of protein. However, the lungs of the fetuses with amniotic shunts contained significantly more PC and DSPC, and the L/S ratio was higher than in the control fetuses. These results suggest that the oligohydramnios produced by an amniotic shunt causes pulmonary hypoplasia, but raises the pulmonary surfactant content of fetal rabbit lung.

Animals↗

[Salivary epidermal growth factor in patients with peptic ulcer].

Recent animal studies suggest salivary epidermal growth factor (EGF) has a cytoprotective effect in the upper GI tract and is one of the important factors to promote the healing of experimental ulcer. The present study was undertaken to clarify the role of salivary EGF in peptic ulcer patients. Saliva samples were collected from 129 endoscopically normal subjects and 232 peptic ulcer patients. Salivary EGF concentration was measured by RIA. Salivary EGF output in normal subjects was 5.26 +/- 0.26 (ng/5 min) (mean +/- SE). Those in patients with gastric ulcer (GU), duodenal ulcer (DU) and gastroduodenal ulcer (GDU) were 10.74 +/- 0.15, 8.13 +/- 0.83 and 9.79 +/- 0.91. EGF output in GU and GDU patients were higher than that in normal subjects respectively. Tractable GU patients (healed within 3 months with regular regimen) had higher EGF output than intractable GU patients. Among tractable GU patients, those who had healing within 8 weeks had higher output. EGF output in patients with recurrent GU was lower than that in non-recurrent GU patients. In 10 GU patients, EGF output became higher in healing stage than in active stage. Salivary EGF may promote the healing and prevent the recurrence of human gastric ulcer.

Adult↗

In vitro antiplatelet profiles of the new thromboxane synthetase inhibitor sodium 2-(1-imidazolylmethyl)-4,5-dihydrobenzo[b]thiophene-6-carboxylate.

The in vitro properties of CS-518 (RS-5186; sodium 2-(1-imidazolylmethyl)- 4,5-dihydrobenzo[b]thiophene-6-carboxylate, CAS 113817-57-5), a new thromboxane (TX) synthetase inhibitor, as an antiplatelet agent were investigated. Incubation of clotting whole blood from man, rabbits, and dogs with CS-518 resulted in a concentration-dependent reduction of TXB2 production and an increase in 6-keto-PGF1 alpha. Similar properties were also observed for ozagrel and isbogrel, but both agents were less effective on TXB2 production. CS-518 inhibited arachidonic acid (AA)- or collagen-induced platelet aggregation in platelet rich plasma (PRP) from man, rabbits and dogs. In addition, antiaggregatory effects of CS-518 were confirmed in whole blood by two methods: impedance method and free platelet count method. TXA2 formation in washed canine platelets in response to AA (0.1 mmol/l) was dose-dependently inhibited by incubation with CS-518. This inhibition by CS-518 was gradually attenuated after platelets were subsequently washed with drug-free buffer, but a dose-dependent inhibition was still observed with platelets that had been washed three times. Ozagrel also inhibited TXB2 formation when incubated with platelets, whereas this inhibition disappeared with platelets only washed once. In contrast, platelets treated with acetylsalicylic acid, an irreversible inhibitor of cyclooxygenase showed a comparable inhibition before and after they were washed three times. These results indicate that CS-518 exerts antiplatelet effects in vitro via potent, selective, and long-lasting but reversible inhibition on TX synthetase.

6-Ketoprostaglandin F1 alpha↗

[Hemopurification in the management of ARDS complicating multiple organ failure].

In the field of critical care medicine, it has been claimed that ARDS often develops as a part of multiple organ failure (MOF). Since multi-modality therapy is necessary in the management of MOF, it is also mandatory even in the management of ARDS. Among the various therapeutic approaches for patients with MOF, hemopurification is one of the most effective therapeutic tools. Various hemopurification methods such as hemodialysis, peritoneal dialysis, hemoadsorption, hemofiltration and plasma exchange have been applied in the management of MOR. However, our recent experiences suggest that continuous hemofiltration (CHF) and/or continuous hemodiafiltration (CHDF) are safest, most easily performed and effective hemopurification in the management of ARDS/MOF. The efficacy of hemopurification in the management of ARDS is summarized as follows. 1) Removal of humoral mediators and causative substances of ARDS following insults such as sepsis and trauma. 2) Treatment of pulmonary interstitial permeability edema which has been claimed to be one of the most important pathological conditions in ARDS. 3) Removal of excess water given as carrier in IVH solution and accumulating in the body. 4) Immunomodulation which has also been considered to be necessary in the treatment or prevention of ARDS.

Hemofiltration↗

[The inhibitory effect of cholecystokinin on phosphatidylcholine synthesis in isolated rat pancreatic acini].

The effects of cholecystokinin (CCK) and other pancreatic secretagogues on phosphatidylcholine (PC) synthesis were studied in isolated rat pancreatic acini. When acini were incubated with [3H] choline in the presence of 1 nM CCK-octapeptide (CCK8) for 60 min, the incorporations of [3H] choline to both water soluble choline metabolites and PC in acini were reduced by CCK8 to 74% and 41% of control, respectively. Pulse-chase study revealed that CCK reduced both the disappearance of phosphocholine and the synthesis of PC. Ca(2+)-mobilizing secretagogues such as carbamylcholine and Ca2+ ionophore A23187 also reduced PC synthesis to the same extent as CCK8. By contrast, neither cAMP-dependent secretagogues such as secretin and dibutyryl cAMP nor a phorbol ester had any effect on PC synthesis in acini. These results suggest that CCK inhibits PC synthesis by inducing both the reduction of choline uptake into acini and the inhibition of CTP: phosphocholine cytidylyltransferase activity. This hormonal regulation of PC synthesis via CDP-choline pathway appears to be mediated by Ca(2+)-dependent pathway but not by cAMP- or protein kinase C-dependent pathway.

Animals↗