Changes in electrophysiological properties in the prostatic portion of vas deferens from spontaneously hypertensive rats.

The main objective of this study has been to analyse the electrophysiological differences in the prostatic portion of vas deferens between spontaneously hypertensive (SHR) and Wistar Kyoto rats (WKY). Resting membrane potentials (RMP) recorded in SHR (-63.8+/-0.

From transcription to cell surface expression, the induction of MHC class II I-A alpha by interferon-gamma in macrophages is regulated at different levels.

Using mouse bone marrow-derived macrophages we determined the role of interferon (IFN)-gamma at the different steps in expression of the I-A alpha chain of MHC class II molecules, from transcription to the cell surface. Levels of transcription, RNA, and protein were low in cells not stimulated with IFN-gamma. Treatment with IFN-gamma for 24 or 48 h induced an increase in mRNA levels (7- and 12-fold) that did not correlate with the increase in transcription (2.

The expression of MHC class II genes in macrophages is cell cycle dependent.

Using different drugs, we stopped the cell cycle of bone marrow-derived macrophages at different points. After IFN-gamma stimulation, macrophages arrested at the G(1) phase of the cell cycle did not increase cell surface expression of the MHC class II IA. This inhibition is specific, because, under the same conditions, IFN-gamma induces the expression of Fcgamma receptors and the inducible NO synthase mRNA.

LPS upregulates MHC class II I-A expression in B lymphocytes at transcriptional and at translational levels.

Major histocompatibility complex (MHC) class II molecules are expressed in a limited number of cell types, including B lymphocytes, dendritic cells and macrophages. Lipopolysaccharide (LPS) increases the surface expression of class II molecules in a murine B-cell line by inducing an increase in I-A protein and I-A mRNA levels. LPS does not modify the rate of mRNA degradation; therefore, the increase in mRNA is due to an increase in transcription.

Adrenergic and purinergic components in bisected vas deferens from spontaneously hypertensive rats.

1. Purinergic and adrenergic components of the contractile response to electrical field stimulation (EFS) have been investigated in epididymal and prostatic portions of Wystar Kyoto (WKY) and spontaneously hypertensive rat (SHR) vas deferens. 2.

Translational control of MHC class II I-A molecules by IFN-gamma.

MHC class II molecules are expressed in a limited number of cell types, including B lymphocytes and macrophages (M phi). IFN-gamma increases the surface expression of class II molecules in a murine B cell line without inducing detectable changes in either I-A or I-A mRNA levels. In bone marrow-derived M phi, IFN-gamma causes an increase in class II expression at both the mRNA and surface levels.

Contribution of inhibitory neurotransmitters to the CCK induced relaxation of the circular muscle of avian ileum.

The sulphated form of cholecystokinin-octapeptide (CCK-OP) induces a concentration-dependent relaxation of the circular muscle of isolated chicken ileum which is unaffected by atropine or propranolol but abolished by tetrodotoxin (TTX). The aim of this study was to investigate whether purinergic (ATP), nitrergic (NO) and peptidergic (VIP) neurons are implicated in the response to CCK-OP. In preparations prerelaxed with ATP, CCK-OP caused a further relaxation (average 46%).

Effect of different calcium channel blockers on inhibitory junction potentials and slow waves in porcine ileum.

The effect of several calcium channel blockers was evaluated: (i) on spontaneous electrical and mechanical activities and (ii) on the response to electrical field stimulation. The study was carried out on whole-thickness preparation of porcine ileum. Glass microelectrodes were used to record membrane potential from smooth muscle cells.

CCK is involved in both peripheral and central mechanisms controlling food intake in chickens.

The aim of this work was to study the involvement of cholecystokinin (CCK) in the control of food intake in chickens. The following aspects were studied: 1) the effects of intravenous and intracerebroventricular sulfated octapeptide of CCK (CCK-8s) on voluntary food intake; 2) the effects of two CCK-receptor antagonists. L-365,260 and L-364,718, on food intake; and 3) the ability of such drugs to block the effects of CCK-8s on food intake in the chicken.

L-364,718 and L-365,260, two CCK antagonists, have no affinity for central benzodiazepine binding sites in chickens.

It has recently been demonstrated that L-365,260, a CCK-B antagonist in mammals, causes an increase in food intake in chickens. In contrast, L-364, 718, a CCK-A antagonist in mammals, shows this effect only at very high dose levels. It has been shown that L-365,260 has very low affinity for chicken CCK receptors.

Central and NO mediated mechanisms are involved in the inhibitory effects of CCK on the chicken cecorectal area.

In chickens CCK-8s induces defecation and causes an inhibition of rectal electrical activity (EA) and an increase in cecal motility. In contrast, CCK-4 inhibits the motility of both rectum and ceca. The cecorectal responses to CCK-8s and CCK-4, given intravenously (i.

Central and peripheral cholecystokinin receptors in chickens differ from those in mammals.

Specific binding for the radioligand [3H]CCK-8s has been identified in chicken brain, hypothalamus, pancreas, gallbladder and caecum membranes. This binding was found to be of high affinity, low capacity and saturable, suggesting the presence of specific CCK receptors in these tissues. Scatchard analysis indicated the existence of a single binding site for each tissue.

Intraluminal lipids modulate avian gastrointestinal motility.

Infusion of lipids into the ileum delays gastric emptying and intestinal transit time in some species. The aim of this study was to characterize the actions of intraluminal lipid infusion on gastrointestinal electrical activity in chickens. Animals were prepared for electromyography with chronic electrodes in stomach, duodenum, and small intestine.

Modulation of the migrating myoelectric complexes by cholecystokinin and gastrin in the gastrointestinal tract of chickens.

Several mammalian avian species, including the chicken, show migrating myoelectric complexes (MMC) both in unfed and fed states. In these species, postprandial hormones seem to modulate but not to disrupt the MMC. To gain more information in this modulatory role, we evaluated the role of cholecystokinin (CCK) vs gastrin on the regulation of intestinal motility in chickens.

Is nitric oxide the final mediator regulating the migrating myoelectric complex cycle?

The main objective was to study the role of nitric oxide (NO) in the conversion of migrating myoelectric complexes (MMC) to the irregular electrical activity characteristic of the postprandial state. Both rats and chickens were implanted with electrodes for electromyography in the small intestine. Intravenous infusion of NG-nitro-L-arginine (L-NNA), a NO synthase inhibitor, induced an organized MMC-like pattern in fed rats.

Effects of cholecystokinin on chicken cecal motility: mechanisms involved.

The aims of this work are to characterize the effects of cholecystokinin (CCK) on chicken ceca and to study in vitro the mechanisms through which such actions are mediated. Longitudinal and circular cecal strips kept in vitro in organ baths were responsive to CCK sulphated octapeptide (CCK-8s). On longitudinal strips the response consisted of a fast phasic contraction followed by a sustained increase in tone which was dose dependent and decreased markedly in the presence of tetrodotoxin (TTX).

Mechanisms mediating the effects of cholecystokinin on avian small intestine longitudinal smooth muscle.

The aims of this study were (1) to define the effects of CCK-8s and related peptides on chicken ileum longitudinal smooth muscle and (2) to explore the mechanisms by which such effects occur. The effects of CCK-8s were assayed in vitro on chicken longitudinal ileal strips. CCK-8s produced contraction of ileal strips (EC50 8.

Effects of temperature on in vitro palmitic acid uptake by chicken and rat intestinal tissue.

The intestinal absorption of fatty acids proceeds by simple or facilitated diffusion, a mechanism which is affected by temperature. However, most studies in this field have not taken into consideration the fact that birds have higher physiological temperature than mammals, the absorption being studied at 37 degrees C in both cases. The aim of this work has been to find out whether the higher palmitic acid (PA) uptake rate in birds (chickens) compared to mammals (rats) is attributable to the differences between their body temperatures (41.

Effects of oleic and elaidic acids on in vitro intestinal uptake of cholesterol in the rat.

The effects of oleic and elaidic acid upon the in vitro intestinal uptake of cholesterol were studied in 9 weeks-old male and female rats. Elaidic acid increases the uptake of cholesterol when compared to oleic acid in both males and females. It is suggested that elaidic acid may enhance the esterification of cholesterol within the enterocyte through being more available for esterification and/or through being preferentially incorporated into cholesterol esters.

Experimental conditions affecting in vitro intestinal incorporation of palmitic acid: a methodological approach.

In the rat, a large number of in vitro studies on intestinal fatty acid uptake have been carried out. However, the results obtained under different experimental conditions are often contradictory. The present work is a critical approach to the experimental aspects which may modify in vitro intestinal uptake of fatty acids.

Rhythmic oscillating complex: characterization, induction, and relationship to MMC in chickens.

Migrating myoelectrical complexes (MMCs) and rhythmic oscillating complexes (ROCs) have been investigated in chickens prepared for electromyography. Animals were chronically implanted with electrodes in stomach, duodenum, jejunum, ileum, ceca, and rectum. MMCs showing phases I-III were found in the jejunum and ileum both in fed and fasted states.

Cecocolonic motility in the chicken. Effects of cholecystokinin.

The aims of this work were 1) to define electromyographically the motility pattern of chicken ceca and colon; 2) to study the changes induced by photoperiod and food intake on the motility of this area and 3) to characterize the motor effects of intravenous (i.v.) cholecystokinin in vivo, measuring changes in electrical activity and intracecal pressure.

Immunohistochemical differentiation of gastrin and cholecystokinin in gastrointestinal tract of chickens.

The presence of cholecystokinin (CCK) in the gastrointestinal tract of chickens has not been well demonstrated, although immunological and chromatographic techniques have shown the presence of intestinal gastrin-CCK-like factors. Recently, a new peptide, structurally related to mammalian CCK, but with a gastrin-like activity, has been isolated from the digestive tract of chickens. The objective of this work has been: 1) to study the presence of gastrin-CCK-like immunoreactivity (IMR) in the digestive tract of chickens; 2) to distinguish chicken gastrin from CCK; and 3) to establish their distribution using specific antibodies.