Calcium influx and spontaneous phasic contractions of portal veins after treatment with reserpine, 6-hydroxydopamine, and cocaine

1978 ◽  
Vol 56 (2) ◽  
pp. 199-201 ◽  
Author(s):  
M. Kaiman ◽  
S. Shibata
Keyword(s):  
Guinea Pig ◽  
Portal Vein ◽  
Calcium Influx ◽  
Phasic Contraction ◽  
Reserpine Treatment ◽  
Portal Veins ◽  
6 Hydroxydopamine ◽  
Induced Changes

Reserpine treatment increased the amplitude of the spontaneous phasic contraction (SPC) of portal veins obtained from rabbit and guinea pig but did not alter that of rat. The amplitude of the SPC of portal veins from these animals was increased after 6-hydroxydopamine (6-OHDA) but was not changed after cocaine treatment. Reserpine-and 6-OHDA-induced changes in portal vein SPC amplitude were accompanied by an increase in 45Ca influx.These results indicate that the elevation in SPC amplitude is accompanied by an increase in calcium influx.

pH-induced changes in calcium: functional consequences and mechanisms of action in guinea pig portal vein

2002 ◽  
Vol 283 (6) ◽  
pp. H2518-H2526 ◽  
Author(s):  
R. D. Smith ◽  
D. A. Eisner ◽  
Susan Wray
Keyword(s):  
Guinea Pig ◽  
Portal Vein ◽  
Surface Membrane ◽  
Mechanisms Of Action ◽  
High K ◽  
Effects Of Ph ◽  
Functional Consequences ◽  
Induced Changes ◽  
Intracellular Alkalinization

The effects of changing extracellular (pHo) and intracellular pH (pHi) on force and the mechanisms involved in the guinea pig portal vein were investigated to better understand the control of tone in this vessel. When pHo was altered, the effects on force and calcium were the same irrespective of whether force had been produced spontaneously by high-K depolarization or by norepinephrine; alkalinization increased tone, and acidification reduced it. Because pHo changes also lead to changes in pHi, we determined whether the effects on force could be explained by these induced pHi changes. It was found, however, that only with spontaneous activity did intracellular alkalinization increase force. In depolarized preparations, force was decreased, and, with norepinephrine, force was initially decreased and then increased. Thus the effects of pHo cannot be explained solely by changes in pHi. The role of the sarcoplasmic reticulum (SR) and surface membrane Ca2+-ATPase on the mechanism were investigated and shown not to be involved. Therefore, it is concluded that both pHo and pHi can have powerful modulatory effects on portal vein tone, that these effects are not identical, and that they are likely to be due to effects of pH on ion channels rather than the SR or plasma membrane Ca2+-ATPase.

Effect of human plasma proteins on spontaneous contractile activity of rat mesenteric portal vein

1990 ◽  
Vol 68 (6) ◽  
pp. 737-743 ◽  
Author(s):  
G. Pillai ◽  
M. C. Sutter
Keyword(s):  
Portal Vein ◽  
Spontaneous Activity ◽  
Plasma Proteins ◽  
Mechanical Response ◽  
Contractile Activity ◽  
Physiological Salt Solution ◽  
Portal Veins ◽  
6 Hydroxydopamine ◽  
Dose Dependent Increase ◽  
Dose Dependent

This study examines the effect of various plasma proteins from man on the spontaneous contractile activity of the rat portal vein. Albumin, γ-globulin, α-globulin, β-globulin (the major plasma proteins), and immunoglobulin IgG (the major immunoglobulin present in the γ-globulin fraction) were obtained commercially. Mesenteric portal vein strips were prepared from rats and placed in a physiological salt solution in muscle baths for the measurement of longitudinal mechanical response. Portal veins exposed to albumin or γ-globulin showed a dose-dependent increase in the spontaneous activity, whereas those exposed to α-globulin or α - and β-globulin together showed a dose-dependent inhibition of spontaneous activity. Immunoglobulin IgG produced a dose-dependent increase in the spontaneous activity similar to that of γ-globulin. The increased spontaneous activity produced by albumin was not prevented by ouabain but was inhibited by phentolamine. Spontaneous contractile activity was stimulated by albumin in the chemically (6-hydroxydopamine) denervated portal vein. These findings indicate that albumin acts in a manner similar to noradrenaline. The increased spontaneous activity caused by γ-globulin (IgG) was inhibited by ouabain or verapamil. The effect of IgG was not dependent on α-adrenergic, cholinergic, histaminergic, serotoninergic, or renin angiotensin systems nor was it affected by removal of the endothelium. These observations may have implications in the pathophysiology of essential hypertension.Key words: vasomotion, mesenteric portal vein, plasma proteins, albumin, γ-globulin, inhibitory factor, stimulatory factor, IgG.

Olprinone for the Treatment, but Not Prevention, of Fatigue-Induced Changes in Guinea-Pig Diaphragmatic Contractility

2003 ◽  
pp. 1679-1782 ◽  
Author(s):  
Aki Uemura ◽  
Yoshitaka Fujii ◽  
Hidenori Toyooka ◽  
Setsuko Suzuki ◽  
Kohei Sawada ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Induced Changes

Drug induced changes in free, labile and stable acetylcholine of guinea-pig brain

1969 ◽  
Vol 18 (6) ◽  
pp. 1315-1324 ◽  
Author(s):  
L. Beani ◽  
C. Bianchi ◽  
P. Megazzini ◽  
L. Ballotti ◽  
G. Bernardi
Keyword(s):  
Guinea Pig ◽  
Drug Induced ◽  
Pig Brain ◽  
Induced Changes ◽  
Guinea Pig Brain

Vasomotion and Contraction in the Perfused Mesenteric–Portal Vein: Effect of Drugs and Altered Perfusion Pressure

1971 ◽  
Vol 49 (6) ◽  
pp. 615-618 ◽  
Author(s):  
H. James Rhodes ◽  
M. C. Sutter
Keyword(s):  
Portal Vein ◽  
Perfusion Pressure ◽  
Splanchnic Circulation ◽  
Intraluminal Pressure ◽  
Longitudinal Tension ◽  
Portal Veins ◽  
Spontaneous Contractions

Isolated rabbit anterior mesenteric–portal veins (A.M.V.) which possess vasomotion were perfused with Kreb's solution in an apparatus designed so that intraluminal pressure and longitudinal tension could be measured simultaneously. The rate of vasomotion increased as perfusion pressure was increased from 0 to approximately 5 or 6 mm Hg. The amplitude of these spontaneous contractions increased to a maximum at a perfusion pressure of approximately 6 mm Hg and then decreased as perfusion pressure was raised further. Noradrenaline (10−7 g/ml) increased the longitudinal tension, but slightly decreased intraluminal pressure. Isopropylnoradrenaline (10−7 g/ml) had little effect on intraluminal pressure but decreased the amplitude of spontaneous contractions. It is suggested that the effect of perfusion pressure on the frequency and amplitude of vasomotion in the A.M.V. is related to autoregulation and that this perfused preparation may be a useful model for study of the rheology and responses to drugs of the splanchnic circulation.

Tumoural portal vein thrombosis

1997 ◽  
Vol 38 (5) ◽  
pp. 655-659
Author(s):  
L. Marti-Bonmati ◽  
E. Lonjedo ◽  
D. Mathieu ◽  
C. Coffin ◽  
C. Poyatos ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Portal Vein ◽  
Imaging Techniques ◽  
Vena Cava ◽  
Tumour Thrombus ◽  
Vein Thrombosis ◽  
Significant Difference ◽  
Before And After ◽  
Portal Veins ◽  
Cellular Carcinoma

Purpose: Intrahepatic thrombus is usually associated with either cirrhosis or hepato-cellular carcinoma (HCC). Most HCCs enhance after the administration of MnDPDP (Teslascan). Our objective was to analyze the enhancement characteristics of tumour portal vein thrombi. Material and Methods: Thrombi affecting the main or segmental portal veins (17 cases) and the suprahepatic inferior vena cava (1 case) were retrospectively selected from a series of 128 patients studied with MR imaging before and after the administration of MnDPDP. Enhancement was assessed qualitatively and quantitatively. Results: All tumour thrombi enhanced after MnDPDP administration. The enhancement was more conspicuous in the GRE images. On the quantitative evaluation, the portal thrombus enhancement was greater for GRE images than SE images. Portal thrombi enhanced more than the liver and the HCCs. There was a significant difference between the enhancement of the HCCs and the thrombi with both MR imaging techniques. Conclusion: The greater enhancement of the tumour thrombus associated with the liver and HCC may suggest that other mechanisms, apart from accumulation of the contrast medium within the hepatocytes inside the thrombi, are involved in thrombus enhancement.

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