摘要:

The movement of neutral amino acids across the blood-brain barrier is bidirectional, however, blood to brain transport is much better characterized than brain to blood transport. Available evidence points to the existence of a single transport system (system L) at the luminal capillary surface. The properties of this system place constraints on possible mechanisms of regulating blood-brain neutral amino acid transport activity. One property, mediation of exchange transport, suggests that amino acid influx is coupled to efflux, particularly efflux of glutamine, synthesized in glial astrocytes from ammonia and glutamic acid. Such a coupling could account for increased blood-brain neutral amino acid transport in liver disease and decreased transport activity after treatment with methionine sulfoximine, a glutamine synthetase inhibitor.

ISSN:0031-7012    

DOI:10.1159/000137466

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Noradrenergic neurotransmission in the electrically stimulated isolated splenic strip of the cat was found to be modulated via opiate receptors. Pharmacodynamic parameters of morphine, methionine-enkephalin, azidomorphine, naloxone and N-cyclopropylmethyl-nor-azidomorphine (CAM) were determined. As CAM proved to be more potent than naloxone in this organ, the cat splenic strip is a useful model for the in vitro testing of opiate B-receptors.

ISSN:0031-7012    

DOI:10.1159/000137467

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

Diethylstilbestrol (DES, 1 x 10–6 M) inhibited norepinephrine (NE)-induced contractions of isolated rat aortic strips only at low doses of NE in contrast to estradiol-17β (1 x 10–5M) which depressed only the response to high doses. The degree of inhibition increased over a period of 90 min exposure to the estrogens. Microsomes accumulated more 14C-DES per milligram protein than any other subcellular fraction of rat aorta. This accumulation process appears to be gradual requiring many minutes which may explain the gradual increase in intensity of the inhibitory effect with increased time of exposure to DES. The contrasting inhibitory effects of DES and estradiol in rat aorta may be due to non-homogeneous solution of these drugs in smooth muscle plasma membranes. DES, but not estradiol, caused contraction of isolated aortic strips prior to the onset of inhibition. This contraction showed fade and tachyphylaxis, was antagonized by α-adrenergic blockers, and was enhanced by prior treatment of the strips with NE. Thus, DES but not estradiol is capable of mobilizing NE from storage sites in rat

ISSN:0031-7012    

DOI:10.1159/000137468

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The effects of exogenously applied prostaglandins on the contractile responses of the gallbladder and sphincter of Oddi isolated from guinea pigs were examined in normal and indomethacin-treated preparations. Indomethacin reduced the tone and the contractile responses to transmural stimulation and to exogenously applied ACh of the gallbladder, while the tone and contractile responses of the sphincter of Oddi were little affected by indomethacin. Prostaglandins E1, E2 and F2α potentiated the contractile responses of the gallbladder to transmural stimulation and ACh, and furthermore, treatment with indomethacin enhanced the potentiating effects of prostaglandins E1 and E2 but not the effect of PGF2α. The reduced tone and contractility of the gallbladder were restored to the control level by addition of PGE1 and PGE2 but not by PGF2α. These results suggest that endogenous PGE1 and PGE2 may play an important role in neurogenic control of contractility of the gallbladder, but not of the sphincter of Od

ISSN:0031-7012    

DOI:10.1159/000137469

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

A factor, present in the kidneys of rats, has been shown to inhibit thyroid activity both in vivo (rat) and in vitro (porcine and bovine thyroid slices). The aim of the present study was to quantitate the inhibitory activity of this factor in renal and other tissues from rats by means of the lactoperoxidase-catalyzed iodination of L-tyrosine. Supernatants of renal homogenates (10,000, 27,000 and 35,000 g) obtained from rats inhibited this in vitro iodination system as well as the lactoperoxidase-catalyzed oxidation of guaiacol. The 35,000-g supernatant from both renal and hepatic tissues contained the greatest inhibitory activity per milligram of protein. Supernatants of homogenates (35,000-g·fraction) from testes contained one eighth to one third the activities of liver and kidney, respectively. Kidneys of other species, including fetal goat, mature goat, fetal lamb, mature monkey and mature dog, were also shown to contain the thyroid-depressing factor. These studies suggest that the thyroid-depressing factor is found mainly in liver and kidneys of the rat and that it is not unique to the rat but is present in the kidneys of other species as well

ISSN:0031-7012    

DOI:10.1159/000137470

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The effect of thyroid dysfunction on the metabolism of halothane (100 ppm), enflurane (100 ppm) and methoxyflurane (300 ppm) was investigated during application by inhalation. In male rats the elimination half-lives from the atmosphere of the exposure system amounted to 0.76 h for halothane, 6.84 h for enflurane and 0.64 h for methoxyflurane. Hyperthyroidism due to three daily injections of 0.1 mg/kg triiodothyronine i.p. significantly shortened the half-lives of all three inhalation anesthetics. Hypothyroidism due to operative removal of the thyroid gland affected the metabolism of halothane only as evidenced by a prolongation of the elimination half4ife while enflurane and methoxyflurane half-lives remained unchanged. The observed differences in metabolic rates are explained by different metabolic pathways of the three compounds. They may be important for the manifestation of toxic effects.

ISSN:0031-7012    

DOI:10.1159/000137471

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

The effect of noradrenaline on the bioelectric activity of the mucous glands of 9 toads was studied by means of intraglandular recording. Noradrenaline induced a transient increase in glandular secretion and a simultaneous two-phase increase in the potential difference of the glands. Perfusion with 0.043 mM ethanol-Ringer’s reversibly reduced this response. Ouabain, in concentrations which block Na+K+-activated ATPase, markedly reduced the slow phase of the response of the’ isolated skin to noradrenaline. The results suggest that ethanol acts in two ways: first by increasing the electrical resistance of the skin and secondly by partially inhibiting the active transport of sodium due to a decrease in permeability of the apical membrane of the transporting ce

ISSN:0031-7012    

DOI:10.1159/000137472

出版商:S. Karger AG    

年代:1981

数据来源: Karger

摘要:

An extract from bovine muscle, prepared by proteolytic digestion, inhibits the development of CCl4-induced liver cirrhosis when administered either subcutaneously or orally to the rat. It has a significant effect on survival time, liver and body weight, and gross and microscopic features, collagen, water, protein and triglyceride content of the liver. It also accelerates the regression of CCl4-induced cirrhosis. Most of these effects were also achieved with a heat-stable or lipid fraction of the extract. The heat-stable fraction also shows anti-inflammatory activity in carrageenan- and egg white-induced edemas and in cotton pellet granuloma.

ISSN:0031-7012    

DOI:10.1159/000137473

出版商:S. Karger AG    

年代:1981

数据来源: Karger

ISSN:0031-7012    

DOI:10.1159/000137474

出版商:S. Karger AG    

年代:1981

数据来源: Karger

ISSN:0031-7012    

DOI:10.1159/000137475

出版商:S. Karger AG    

年代:1981

数据来源: Karger