摘要:

The effects of the ionophore, RO 2-2985 (X537A, RO) were studied on isolated coronary, renal and femoral arteries in two types of experiments: (l) the effect of RO as a modulator of various contractile effects of KCl and phenylephrine (PE), and (2) the effect of RO itself as a contractile agonist. The effect of the ionophore A23187 was observed in similar experiments to help determine the nature of the RO response. In the first type of experiment, RO was found to have a differential effect upon the arteries contracted with KCl. The coronary arteries relaxed upon addition of the ionophore, whereas, the femoral and renal arteries did not. A23187 had only a transient effect on KCl-contracted coronary arteries. RO relaxed femoral and renal arteries contracted with PE, and A23 187 had only a transient effect. RO attenuated ED50 values and maximum tension developments to both KCl and PE, and A23187 had no effect on these parameters. In the second type of experiment, RO (only at 10–5M) was found to contract femoral and coronary arteries, but had no effect on renal arteries. Experiments with α-blocking agents and calculations using association constants of RO for catecholamines suggest that RO is not acting via catecholamine chelation. The dissimilarity between the effects of RO and A23187 suggest that RO may not be working through a specific effect on Ca++. These differential responses to RO suggest variations in intervessel regulation of PE- and KCl-induced contractions and can explain, in part, the in vivo effects of RO on regional blood fl

ISSN:1018-1172    

DOI:10.1159/000158218

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The effect of glucose withdrawal upon mechanical activity and the redox level of pyridine nucleotides and flavoproteins was investigated in isolated rat portal veins under aerobic conditions. A decrease of extracellular glucose concentration correlated with contractile activity. During acetylcholine-induced tetanic contractions, NADH and flavoproteins were oxydized only in vessels supplied with glucose. The myogenic activity was restituted when glucose was added after withdrawal parallel with a reduction of NAD and flavoproteins. The results suggest that glucose, besides its effect on the energy metabolism, has an influence on the excitability of smooth muscle cells of rat portal veins.

ISSN:1018-1172    

DOI:10.1159/000158219

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

This study examined the effect of exogenously applied adenosine on the release of 3H-norepinephrine from the field-stimulated, superfused rat portal vein. Adenosine was found to inhibit the field-stimulated release of 3H-norepinephrine in a dose-dependent manner in 50- to 1,000-µM concentrations. The effect was reversed when adenosine was washed out. The inhibitory effects of adenosine were antagonized by theophylline (10–4M) which by itself showed a slight enhancement of stimulated 3H-norepinephrine release. ATP was found to inhibit 3H-norepinephrine release at the same concentration as adenosine while inosine was inactive. When adenosine was tested in the presence of the muscarinic and α-adrenergic blocking agents atropine and phenoxybenzamine along with indomethacin, a prostaglandin synthesis inhibitor, its inhibitory effect on the stimulated release of 3H-norepinephrine persisted. It is concluded that adenosine and/or ATP can modulate the nerve-stimulated induced release of norepinephrine presumably by an action on the adrenergic nerve termin

ISSN:1018-1172    

DOI:10.1159/000158220

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Mast cells are relatively common in human omental veins where they generally occur in the tunica adventitia and among the peripheral smooth muscle cells of the tunica media. The distance between mast cells and adjacent muscle cells is often as short as 1 µm. The tunica intima does not contain mast cells. With few exceptions the typical mast cells were oval in shape, had numerous slender projections and contained granules (0.3–0.7 µm) with characteristic stacks of lamellae and scrolls. A few elongated cells with processes containing granules filled with dense homogeneous matrix material were also detected and could represent so-called chromaffin mast cells. Noradrenergic axons and terminals identified by their large (85 nm) and small (50 nm) dense-cored vesicles are present in the vicinity of many mast cells which could allow various interactions between the two cell types and their released amines and ATP. Electrical field stimulation which affects the nerve terminals does not change the ultrastructure of the mast cells unless the α-blocking agent phentolamine (7.5 × 10-7 M) is present during the stimulation, when degranulation re

ISSN:1018-1172    

DOI:10.1159/000158221

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158222

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158223

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158224

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158225

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158217

出版商:S. Karger AG    

年代:1979

数据来源: Karger