摘要:

Effects of amino acids and dipeptides on ethanol (50 mM) absorption were studied by in vivo perfusion of the rat intestine. All the amino acids and dipeptides tested enhanced the rate of ethanol absorption over that observed with a control solution containing an equimolar concentration of mannitol. The increase in the rate of ethanol absorption can be related to the entry of ethanol with water which accompanies the active absorption of these nutrients. Some amino acids and dipeptides like lysine, tryptophan and glycyl-phenylalanine have an additional stimulatory effect on ethanol absorption which seems unrelated to water movement.

ISSN:0031-7012    

DOI:10.1159/000137548

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

In conscious rats, histamine given intraperitoneally produced a delay in gastric emptying. A dose-dependent relationship was observed. The threshold dose was about 1 mg/kg, the calculated maximum dose 35 mg/kg. The inhibitory effect of histamine on gastric emptying was abolished by pretreatment with H1-receptor antagonists and mimicked by 2-aminoethylthiazole; on the contrary, an H2-receptor agonist (dimaprit) and H2 antagonists were completely ineffective. This suggested that receptors involved in delay of gastric emptying are of the H1 type. The inhibitory effect of histamine on gastric emptying was not modified by pretreatment with the well-known inhibitors of gastric secretion, metiamide and cimetidine. This is consistent with the idea that the delay in gastric emptying observed with histamine may not be related to the gastric secretory properties of this compound.

ISSN:0031-7012    

DOI:10.1159/000137549

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

A high-performance liquid chromatography method is described which allows for the simultaneous determination of antipyrine, 4-hydroxyantipyrine, norantipyrine and 3-hydroxyantipyrine. Hydrolysis conditions with respect to source of glucuronidase, amount of glucuronidase, pH of incubation and addition of antioxidant to the incubation medium proved to be very critical for norantipyrine and to a lesser extent 4-hydroxyantipyrine. The method is of good sensitivity, specificity, accuracy and reproducibility. Thus, the method is well suited for detailed metabolic studies.

ISSN:0031-7012    

DOI:10.1159/000137550

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Human liver N-acetyltransferase (NAT) activity undergoes rapid inactivation after death. Thus, in vitro determination of acetylator phenotype in liver autopsies may be unreliable. In the present investigation, the relative stabilities of monomorphic and polymorphic NAT activity were compared in situ in human and rabbit liver of rapid and slow acetylator phenotype. In both phenotypes, the monomorphic NAT activity was considerably less stable than the polymorphic, enabling it to be utilized as an enzyme marker to assure reliable in vitro phenotype classification.

ISSN:0031-7012    

DOI:10.1159/000137551

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Rat liver microsomes contained two methyltransferases which converted phosphatidylethanolamine (PE) to phosphatidylcholine (PC). The first methyltransferase converted PE to phosphatidyl-N-methylethanolamine (PME) and the second methyltransferase converted PME to PC. Previous work has shown that increased PME synthesis decreases membrane microviscosity. Therefore, changes in the rat liver microsomal cytochrome P-450, phospholipid methyltransferases and membrane microviscosity after induction by phenobarbital and 3-methylcholanthrene were studied. Phenobarbital and 3-methylcholanthrene increased cytochrome P-450 levels 2- to 3-fold. At low SAM concentration, the proportion of PME among the total phospholipids formed increased significantly, and at a high SAM concentration, the proportion of PC among the total phospholipids formed decreased significantly in microsomes of treated rats. Treatment of rats with phenobarbital and 3-methylcholanthrene also decreased microviscosities of the microsomal membranes and liposomes which were prepared from phospholipids extracted from the microsomes. In synthetic liposomes containing PE, PME and PC, microviscosity decreased when the proportion of PME was increased or the proportion of PC was decreased. These results suggest that the membrane fluidity increases with phenobarbital and 3-methylcholanthrene treatment, and changes in phospholipid methyltransferases may contribute to the process of enzyme induction. During induction with phenobarbital, all three factors known to increase membrane fluidity (linoleic

ISSN:0031-7012    

DOI:10.1159/000137552

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Acute administration of certain cannabinoids, including Δ9-tetrahydrocannabinol (Δ9-THC), resulted in elevated levels of plasma corticosterone in mice. The rank order potency of these cannabinoids is the same as others have reported using behavioral tests. The maximally effective dose of Δ9-THC (30 mg/kg) in this test also increased the amount of 3H-tryptophan found in the brains of mice given an intravenous injection of 3H-tryptophan 10 min prior to decapitation. This effect was associated with an increase in the amount of 3H-5-hydroxytryptamine synthesized during the pulse period. Adrenalectomy was found to inhibit these effects of Δ9-THC. The possibility that corticosterone may mediate the effects of Δ9-THC on tryptophan disposition and metabolism is discu

ISSN:0031-7012    

DOI:10.1159/000137553

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

When Prozime-10 (P-10), a protease extracted from cultured broth of Aspergillus melleus, was injected intravenously into anesthetized dogs, plasma ACTH was increased with a latency of 30 min, and this was followed by remarkable elevation of plasma cortisol in many instances. A similar increase in plasma cortisol was elicited after trypsin and α-chymotrypsin were injected. Plasma histamine was raised promptly prior to an increase in plasma ACTH after P-10 in every case. However, in certain cases, changes in cortisol occurred simultaneously with ACTH after P-10. Such a rapid elevation of cortisol can be explained, partly, by direct stimulation of the adrenal cortex by histamine

ISSN:0031-7012    

DOI:10.1159/000137554

出版商:S. Karger AG    

年代:1981

数据来源: Karger