STUDIES ON THE MECHANISM OF NIDATION. XXXIII.

1968 ◽  
Vol 57 (1) ◽  
pp. 136-141 ◽  
Author(s):  
G. J. Marcus ◽  
M. C. Shelesnyak
Keyword(s):  
Histamine Release ◽  
Seminal Plasma ◽  
Histamine Content ◽  
Rat Uterus ◽  
Pregnant Rat ◽  
Low Level ◽  
Level Characteristic ◽  
Electrical Induction

ABSTRACT In an extension of previous studies which had shown that decidual induction in the rat depends on the availability of histamine, the possibility that exposure of the rat uterus to semen influences the availability of histamine in the uterus was investigated. The histamine content of the rat uterus was measured following normal mating (uterus exposed to seminal plasma plus sperm), following mating with vasectomized males (uterus exposed to seminal plasma only) and following electrical induction of pseudopregnancy. Mating with vasectomized males resulted in an elevation of the histamine content of the uterus from the low level characteristic of electrically induced pseudopregnancy to approximately the level characteristic of pregnancy in the preimplantation period. Histamine-release, which occurs at the time of decidual induction in the pregnant rat, did not occur in the uterus of the rats mated with vasectomized males. The elevation in histamine following mating was attributed to importation by cells infiltrating the uterus in response to the stimulus of mating. The non-release of histamine was attributed to the lack of stimulation in the absence of the blastocyst.

STUDIES ON THE MECHANISM OF NIDATION: X.

1964 ◽  
Vol 47 (2) ◽  
pp. 255-264 ◽  
Author(s):  
G. J. Marcus ◽  
M. C. Shelesnyak ◽  
P. F. Kraicer
Keyword(s):  
Histamine Release ◽  
Significant Degree ◽  
Histamine Level ◽  
Histamine Content ◽  
Rat Uterus ◽  
Sequence Of Events ◽  
No Release ◽  
Significant Release ◽  
In Pregnancy

ABSTRACT Accumulated evidence suggested the occurrence of the following sequence of events in nidation in the rat: An oestrogen-surge, occurring on day L3 of pregnancy, releases histamine in the uterus; the liberated histamine stimulates the progestational endometrium, inducing decidualization. Since an oestrogen-surge occurs also during pseudopregnancy, the same sequelae, culminating in decidualization, are to be invariably expected. The present study was undertaken to determine the basis for the rarity of spontaneous decidualization in the pseudopregnant rat. Measurement of day to day changes in the histamine content of the rat uterus confirmed the occurrence of histamine-release following the oestrogen-surge of pregnancy. During pseudopregnancy, however, following the histamine decline after oestrus, a high histamine level is not re-established as in pregnancy but the histamine content remains low and no release is observed after the oestrogen-surge of pseudopregnancy. Supplementing the surge oestrogen with exogenous oestradiol or oestriol in doses as great as 40 μg failed to induce a significant degree of decidualization in the pseudopregnant rat, indicating that no significant release of histamine was induced. The rarity of spontaneous decidualization in the pseudopregnant rat therefore is due to the absence of a pool of histamine amenable to release by oestrogen. It is, therefore, apparent that hormonal influences on the uterus are not identical in pseudopregnancy and in pregnancy.

scholarly journals Identification of myoelectric signals of pregnant rat uterus: new method to detect myometrial contraction

2017 ◽  
Vol 58 (2) ◽  
pp. 141-148 ◽  
Author(s):  
Kálmán F. Szűcs ◽  
György Grosz ◽  
Miklós Süle ◽  
Anikó Nagy ◽  
Zita Tiszai ◽  
...  
Keyword(s):  
New Method ◽  
Rat Uterus ◽  
Myoelectric Signals ◽  
Pregnant Rat

Effect of hypothermia on histamine release induced by epinephrine infusion

1960 ◽  
Vol 199 (2) ◽  
pp. 272-274 ◽  
Author(s):  
T. Szilagyi ◽  
A. Kover ◽  
B. Csaba
Keyword(s):  
Histamine Release ◽  
Femoral Artery ◽  
Saphenous Vein ◽  
Histamine Level ◽  
Histamine Content ◽  
Epinephrine Infusion

Experiments were performed on dogs anesthetized with chloralose. Epinephrine was infused (20 µg/kg/min.) into the saphenous vein and blood was taken from the femoral artery. Diffusible histamine contents of the plasma were estimated with the superfusion method. It was found that in normothermia epinephrine infusion results in a considerable rise of histamine level. After the cooling of the animals (21.5°–23°C) histamine release does not take place at all during and after the epinephrine infusion, and the histamine content of the blood does not change.

Fast Na+ channels in smooth muscle from pregnant rat uterus

1992 ◽  
Vol 70 (4) ◽  
pp. 491-500 ◽  
Author(s):  
Nicholas Sperelakis ◽  
Yoshihito Inoue ◽  
Yusuke Ohya
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Current Density ◽  
Sodium Current ◽  
Muscle Cells ◽  
Slow Inward Current ◽  
Rat Uterus ◽  
Pregnant Rat ◽  
Inward Current ◽  
Channel Current

Smooth muscle cells normally do not possess fast Na+ channels, but inward current is carried through two types of Ca2+ channels: slow (L type) Ca2+ channels and fast (T type) Ca2+ channels. Whole-cell voltage clamp was done on single smooth muscle cells isolated from the longitudinal layer of the 18-day pregnant rat uterus. Depolarizing pulses, applied from a holding potential of −90 mV, evoked two types of inward current, fast and slow. The fast inward current decayed within 30 ms, depended on [Na]o, and was inhibited by tetrodotoxin (TTX) (K0.5 = 27 nM). The slow inward current decayed slowly, was dependent on [Ca]o (or Ba2+), and was inhibited by nifedipine. These results suggest that the fast inward current is a fast Na+ channel current and that the slow inward current is a Ca2+ slow channel current. A fast-inactivating Ca2+ channel current was not evident. We conclude that the ion channels that generate inward currents in pregnant rat uterine cells are TTX-sensitive fast Na+ channels and dihydropyridine-sensitive slow Ca2+ channels. The number of fast Na+ channels increased during gestation. The averaged current density increased from 0 on day 5, to 0.19 on day 9, to 0.56 on day 14, to 0.90 on day 18, and to 0.86 pA/pF on day 21. This almost linear increase occurs because of an increase in the fraction of cells that possess fast Na+ channels. The Ca2+ channel current density was also higher during the latter half of gestation. These results indicate that the fast Na+ channels and Ca2+ slow channels in myometrium become more numerous as term approaches, and we suggest that the fast Na+ current may be involved in spread of excitation. Isoproterenol (β-agonist) did not affect either ICa(s) or INa(f), whereas Mg2+ (K0.5 = 12 mM) and nifedipine (K0.5 = 3.3 nM) depressed ICa(s). Oxytocin had no effect on INa(f) and actually depressed ICa(s) to a small extent. Therefore, the tocolytic action of β-agonists cannot be explained by an inhibition of ICa(s), whereas that of Mg2+ can be so explained. The stimulating action of oxytocin on uterine contractions cannot be explained by a stimulation of ICa(s).Key words: sodium current, fast sodium current, calcium currents, myometrial smooth muscle cells, pregnant uterine muscle.

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