Abstract:
:The purpose of the present work was to study the rate of basal luteinizing hormone (LH) glycosylation, discriminating the co-translational (proximal) and the post-translational (distal) glycosylation. The experiments were performed to determine the temporal relationship between the biosynthesis of the peptide chains (by [14C]leucine incorporation: [14C]Leu-LH) and the proximal (by [3H]mannose incorporation: [3H]Man-LH) and distal (by [3H]galactose incorporation: [3H]Gal-LH) glycosylation of LH, by rat pituitary cells in primary culture. In addition, the effects of cycloheximide (translation inhibitor) and tunicamycin (glycosylation inhibitor) on the rates of synthesis and release of [3H]Man-LH and [3H]Gal-LH were studied. The rates of synthesis and release (between 0 and 2 h and between 2 and 5 h) were calculated by regression analysis and the statistical significance of differences was determined by the slope test. The rate of synthesis of [3H]Man-LH (slope = 45.59) parallelled that of [14C]Leu-LH (slope = 41.39), which was in agreement with the assumption that the addition of the high mannose core is a co-translational event. Release of [3H]Man-LH (slope = 4.32) as well as that of [14C]Leu-LH (slope = 2.53) showed a lag period of approximately 2 h. The dynamics of [3H]Gal-LH secretion over the course of incubation, with a slower rate of synthesis (slope = 26.40) and a faster rate of release (slope = 6.34), differed from that of [3H]Man-LH. LH labeled with [3H]Gal was released from the early times of the incubation, indicating that galactose is added in the final stages of the secretory process into LH molecules, which are immediately released. LH translation blockage induced by cycloheximide was associated with a corresponding decrease of [3H]Man incorporation. On the other hand, addition of tunicamycin to the pituitary cells inhibited the rates of synthesis and release of [3H]Man-LH, without affecting those of [14C]Leu-LH. These findings show that proximal glycosylation depends on synthesis of the peptide chains, whereas the addition of the polymannose core is not a condition for translation. The rates of synthesis and release of [3H]Gal-LH were less affected by the antibiotics, and the inhibition was only significant at higher doses and long-time treatments. The present results demonstrate the independence of both steps of LH glycosylation, the rate of [3H]Gal-LH synthesis being 1.7-fold slower and that of release 1.5-fold faster than those of [3H]Man-LH, respectively. The data also suggest that glycosylation is not an essential step in the LH secretory process since the hormone, which is normally secreted in a glycosylated form, was synthesized, transported, and released without the carbohydrate side chains.
journal_name
Can J Physiol Pharmacoljournal_title
Canadian journal of physiology and pharmacologyauthors
Pérez GT,Apfelbaum MEsubject
Has Abstractpub_date
1997-07-01 00:00:00pages
825-31issue
7eissn
0008-4212issn
1205-7541journal_volume
75pub_type
杂志文章abstract::Fetal and neonatal rats received daily subcutaneous injections of 10 microgram thyrotropin-releasing hormone (TRH) until 7 or 14 days postnatally. At 70 days the pups were challenged with 1 microgram TRH intravenously via an indwelling jugular cannula. Basal serum thyroxine, triiodothyronine, and thyroid-stimulating h...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y79-004
更新日期:1979-01-01 00:00:00
abstract::In using pharmacologic stimuli, force-velocity (FV) curves are usually obtained by the method of quick release (QR) and redevelopment of shortening at peak tetanic tension; the advantage of the method being that the active state is at maximum. However, the QR may itself reduce the intensity of the active state and res...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y85-008
更新日期:1985-01-01 00:00:00
abstract::Caffeine has been reported to have a positive and (or) a negative inotropic effect on cardiac muscle. In this study, the force-frequency and postrest characteristics of rat atrium were studied in the presence of caffeine (1.0-10 mM) to see if the interval between beats affected the response of cardiac muscle to caffei...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y92-034
更新日期:1992-02-01 00:00:00
abstract::A simple method using gas chromatography-mass spectrometry was developed to determine a low concentration of ethanol in urine. The detection limit was 0.02 mM ethanol. A mean +/- SD ethanol concentration in urine of 0.21 +/- 0.17 mM was measured in 11 alcoholics after 14 days abstention, a level at least 10 times high...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y87-193
更新日期:1987-06-01 00:00:00
abstract::Methimazole was previously shown to protect rats, mice, and (or) dogs against cisplatin-, cephaloridine-, 2-bromohydro-quinone-, and S-(1,2-dichlorovinyl)-L-cysteine-induced nephrotoxicity. In this study, methimazole effects on gentamicin (GM) induced nephrotoxicity were examined. Rats given GM (40 mg/kg) twice daily ...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y94-176
更新日期:1994-10-01 00:00:00
abstract::Pertussis toxin (PTX) is a heterohexameric protein, which is divided into subunits A and B. The A-subunit (protomer) possesses adenine diphosphate (ADP) ribosyltransferase activity, and the B-oligomer confers cell surface binding specificity on the toxin. By virtue of the ADP-ribosylation activity in the A-subunit, PT...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-74-5-559
更新日期:1996-05-01 00:00:00
abstract::The inotropic response induced by beta-adrenergic and H1 histaminergic receptor stimulation was characterized in guinea pig left atria by obtaining dose-response relationships for isoproterenol and histamine under various experimental conditions. Conditions (hypothermia, high frequencies of stimulation, and large extr...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y78-147
更新日期:1978-12-01 00:00:00
abstract::The major hallmark of rotator cuff tendinopathies (RCT) is the disorganization of tendon extracellular matrix (ECM) which is due to decrease in the collagen I-to-collagen III ratio. In addition, the pathology of tendon matrisome remains asymptomatic and hypoxia has been identified to be the priming signal to initiate ...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2020-0314
更新日期:2020-08-15 00:00:00
abstract::Amiodarone is a new antiarrhythmic drug, commonly coadministered with digoxin in various cardiac disorders. Amiodarone caused a 10-fold increase of serum digoxin in rats, when the two drugs were simultaneously administered. Amiodarone significantly reduced digoxin uptake by renal cortical slices in the rat, and failed...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y83-212
更新日期:1983-12-01 00:00:00
abstract::The rat atrium contains a potent natriuretic factor which appears to inhibit the sodium reabsorption in the collecting tubules of the kidneys. We examined the effects of the injection of partially purified atrial natriuretic factor (ANF) and synthetic ANF (8-33) into rats with simultaneous infusions of dextrose or apr...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y84-105
更新日期:1984-06-01 00:00:00
abstract::The experiment examined biological responses produced by combined sequential exposure to low-level tritium contamination, followed by challenging irradiation with fast neutrons. Modifications of endogenous antioxidant potential of different organs in rats were discussed in relation to tissue radiosensitivity. Rats pre...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y02-089
更新日期:2002-07-01 00:00:00
abstract::Coronary flow was recorded from spontaneously beating isolated perfused hearts of rats and guinea pigs. Arachidonic acid (AA), in single bolus doses, produced a fast short lasting coronary constriction followed by a slow developing but persisting vasodilation. These reactions (biphasic type) were characteristic of the...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y84-211
更新日期:1984-10-01 00:00:00
abstract::The sodium-hydrogen exchanger (NHE) helps the cell to recover from intracellular acidosis. In this study, we have investigated the effect of HOE 642 (a specific NHE1 blocker) on papillary muscles from rats and guinea pigs during transient acidosis and PKC activation by recording developed force (DF), action potential ...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y03-091
更新日期:2003-10-01 00:00:00
abstract::In addition to bronchial smooth muscle, histamine and other mediators act in bronchial asthma on the microcirculation of pulmonary connective tissue. The mediators induce enhanced blood flow, and by acting on the blood-tissue barrier, they induce increase in vasopermeability with edema and in more severe injury microh...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章,评审
doi:10.1139/y87-077
更新日期:1987-03-01 00:00:00
abstract::The effect of intracerebroventricular (i.c.v.) injection of the alpha 2-adrenoceptor agonists clonidine and B-HT 920 on mean arterial pressure (MAP), heart rate (HR), and plasma concentrations of noradrenaline and adrenaline was examined in conscious unrestrained rats. The injection of 1.0 microgram clonidine signific...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y88-237
更新日期:1988-11-01 00:00:00
abstract::Because the excessive apoptosis of articular chondrocytes contributes to extracellular matrix (ECM) loss and cartilage damage in rheumatoid arthritis (RA), inhibiting chondrocyte apoptosis might be a promising strategy for RA. Aquaporin1 (AQP1) is overexpressed in RA cartilage and synovial tissues, and play a vital pa...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2018-0334
更新日期:2018-11-01 00:00:00
abstract::Tachykinin receptors in guinea-pig airways were examined using radioligand binding techniques in lung homogenates, and using isolated bronchial segments. Binding of the NK1 selective radioligand 125I-labelled Bolton-Hunter [Sar9,Met(O2)11]substance P ([125I]BHSarSP) was saturable and of high affinity (KD, 0.26 nM). Th...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y95-126
更新日期:1995-07-01 00:00:00
abstract::The intestinal uptake of 0.5 and 40 mM glucose, galactose, and 3-O-methyl glucose (3-O-MG) was examined in vitro in rabbits fed a high (HS) or a low (LS) sucrose diet. In animals with an intact intestinal tract, the jejunal uptake of 0.5 mM 3-O-MG was unaffected by the dietary content of sucrose, whereas the uptake of...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y87-361
更新日期:1987-11-01 00:00:00
abstract::Rapamycin, a new antifungal antibiotic, was found to inhibit the immune response in rats. It totally prevented the development of two experimental immunopathies (experimental allergic encephalomyelitis (EAE) and adjuvant arthritis (AA)) and the formation of humoral (IgE-like) antibody. It was about half as potent as c...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y77-007
更新日期:1977-02-01 00:00:00
abstract::Salvianolic acid B (Sal B) exerts strong antioxidant activity and eliminates the free radical effect. However, how it affects the antioxidant pathway is not very clear. The objective of this study was to investigate the underlying mechanism of Sal B in CCl4-induced acute liver injury, especially its effect on the Nrf2...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/cjpp-2019-0349
更新日期:2020-03-01 00:00:00
abstract::The effect of hepoxilin A, a newly isolated hydroxyepoxide metabolite of arachidonic acid, on calcium transport across the visceral yolk sac membrane of the guinea pig was investigated in vitro in Ussing chambers. While 1-14C-labelled hepoxilin A itself was not transported across the membrane, it increased the rate of...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y84-243
更新日期:1984-12-01 00:00:00
abstract::Lectins, known to recognize endothelial cell adhesion molecules, have been shown to release endothelium-derived relaxing factor (EDRF) from blood vessels. We investigated the effects of different leukocyte-type cells to determine if these cells, by interacting with the endothelium, could release EDRF from the circumfl...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y95-052
更新日期:1995-03-01 00:00:00
abstract::Existing literature provides an equivocal picture of the behavior of mitochondrial synthesis during the time course of cardiac hypertrophy. Therefore, we examined the effect of cardiac hypertrophy on mitochondrial cytochrome c oxidase (CYTOX) activity, the content of CYTOX subunit VIc mRNA, and the expression of molec...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y95-080
更新日期:1995-05-01 00:00:00
abstract::Taurine status and pregnancy outcome were assessed in rats fed low dietary taurine and varying doses of guanidinoethyl sulfonate (GES), a structural analogue of taurine. Female Sprague-Dawley rats (225-270 g) were mated overnight and assigned to one of four groups from day 0 to 20 of gestation. Taurine-deficient anima...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y95-161
更新日期:1995-08-01 00:00:00
abstract::Endothelin-1 has emerged as an important participant in the pathophysiology of a variety of cardiovascular diseases, where it may act on endocrine, paracrine and autocrine bases. Here we review its regulated biosynthesis, receptor-mediated signaling, and functional consequences in the heart, with particular emphasis o...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章,评审
doi:10.1139/y05-002
更新日期:2005-01-01 00:00:00
abstract::Raloxifene (RLX), a selective oestrogen receptor modulator, has oestrogen-agonist effects on bone, lipoproteins, and homocysteine and oestrogen-antagonist activity in the breast and uterus, positioning it as a potential drug for long-term prevention of coronary heart disease in postmenopausal women. To further evaluat...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 临床试验,杂志文章
doi:10.1139/y10-002
更新日期:2010-05-01 00:00:00
abstract::Despite the widespread use of furosemide in the treatment of various fluid and electrolyte disorders in the preterm and term human infant and child, the physiological effects of this potent diuretic agent on renal function and renin release during postnatal maturation are poorly understood. To test the hypothesis that...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y95-015
更新日期:1995-01-01 00:00:00
abstract::The mammalian daily (circadian) clock is located in the suprachiasmatic nuclei of the hypothalamus. Clock function can be detected by the measurement of the circadian change in spontaneous firing rate of suprachiasmatic nuclei cells in a brain slice preparation in vitro. We investigated the effects of neuropeptide Y o...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:
更新日期:2000-02-01 00:00:00
abstract::Infusion of glucose alone or glucose with insulin in cats subjected to acute myocardial ischemia did not alter the hemodynamic response of the cats to coronary artery ligation. Furthermore, determination of myocardial creatine phosphokinase (CPK) (ATP:creatine N-phosphotransferase, EC 2.7.3.2) activities failed to rev...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y76-060
更新日期:1976-08-01 00:00:00
abstract::The effects of some components of ischemia on the oscillatory (Vos) and nonoscillatory (V(ex)) potentials and respective currents (Ios and Iex), as well as their mechanisms, were studied in guinea pig isolated ventricular myocytes by means of a single-microelectrode, discontinuous voltage clamp method. Repetitive acti...
journal_title:Canadian journal of physiology and pharmacology
pub_type: 杂志文章
doi:10.1139/y94-056
更新日期:1994-04-01 00:00:00