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Biomedical subjects

S Batra

Publications and source records attributed to S Batra.

At least 199 records · Page 11Linked to original sources
PubMed1979

Interrelations between plasma and tissue concentrations of 17 beta-oestradiol and progesterone during human pregnancy.

Oestradiol and progesterone concentration in plasma, decidua, myometrium and placenta obtained from women undergoing Caesarian section at term and abortion at weeks 16-22 of pregnancy were determined. There was a significant increase in oestradiol concentration (per g wet wt) both in placenta, decidua and myometrium from mid-term to term. Both at mid-term and term oestradiol concentrations in decidua and myometrium were much smaller than those in the plasma (per ml). Progesterone concentration in placenta and in myometrium did not increase from mid-term to term where it increased significantly in decidua. Decidual and myometrial progesterone concentrations at mid-term were 2-3 times higher than those in plasma, but at term the concentrations in both these tissues were lower than in plasma. The ratio progesterone/oestradiol in plasma, decidua, myometrium and placenta at mid-term was 8.7, 112.2, 61.4 and 370.0, respectively, and it decreased significantly in the myometrium and placenta but was nearly unchanged in plasma and decidua at term. The general conclusion to be drawn from the present study is the lack of correspondence between the plasma concentrations and the tissue concentrations of female sex steroids during pregnancy.

Decidua↗
PubMed1979

Progesterone effects on the evolution of myometrial activity in vivo in the non-pregnant rabbit.

In order to study the influence of progesterone on the myometrial activity ovarian secretion of progesterone was stimulated by intravenous injection of human chorion gonadotrophin (HCG, 75 IU) in 9 nonpregnant rabbits. 4 rabbits, used as controls, were given only saline. Plasma progesterone concentration in blood samples taken at frequent intervals (2-4 h) during the recording was measured by radioimmunoassay. In the controls, the myometrial activity and the plasma levels of progesterone did not change. After 1 h of HCG administration the amplitude of contraction began to decrease and the frequency began to increase after 3 h. After about 5 h the changes in amplitude and frequency were generally fully developed. This pattern of myometrial activity persisted throughout the recording period (12 h) and was also present in recordings made after 24 and 48 h of HCG injection. A maximal increase in plasma progesterone concentration (5.0 ng/ml) had already occurred by 2 h after the HCG injection and gradually decreased thereafter. It is concluded that an elevation in the level of progesterone in non-pregnant rabbits resulting from increased ovarian output (through HCG) has a pronounced and immediate depressing effect on the character of myometrial activity which is indicative of a shift from nonpregnant to pregnant type.

Animals↗
PubMed1979

Relationship between plasma and uterine oestradiol in pseudopregnant rabbits.

Plasma oestradiol concentrations did not change during hCG-induced pseudopregnancy except for a slight increase on Day 18. However, a marked decline was observed in tissue oestradiol on Day 3 whether expressed on the basis of tissue wet weight or protein. The lowest concentration was found at Day 6 but the Day 18 values were comparable to those of untreated controls.

Animals↗
PubMed1979

Prostaglandin-induced luteolysis in pregnant and pseudopregnant rabbits and the resultant effects on the myometrial activity.

The effect of prostaglandin (PG)-induced luteolysis on the myometrial activity in 20--21-day-pregnant and 11--12-day-pseudopregnant rabbits was studied by intrauterine pressure (IUP) recording during PG infusions. The same dose of PG (10 micrograms/h during 8h) was also given to 7 non-pregnant (untreated) does that were used as controls. Peripheral plasma concentration of progesterone and oestradiol-17 beta were measured at 2-h intervals during the infusion. Plasma progesterone level decreased significantly within 2 h or the start of infusion in pregnant and pseudopregnant does and continued to decrease; at the end of 8 h, the concentrations were 31 and 41%, respectively, of the pre-infusion levels. The amplitude of uterine contractions increased significantly after 4 h in pseudopregnant does, increased slightly but insignificantly in the pregnant does and showed no significant change in the non-pregnant does during PG infusion. The amplitudes developed in the pregnant and pseudopregnant does were significantly different. The direct effect of progesterone (1--3 micrograms/h during 4 h) was also studied in 7 non-pregnant rabbits. After 2 h the amplitude of contractions had decreased markedly and the pattern of activity had become irregular. The results support the concept of a myometrial inhibitory factor other than progesterone in rabbit pregnancy and suggest that this factor(s) originates in conceptus.

Animals↗
PubMed1978

Human placental lactogen, estradiol-17beta, and progesterone levels in the third trimester and their respective values for detecting twin pregnancy.

Plasma levels of HPL, P, and E2 was serially measured between weeks 30 to 36 in simplex and duplex pregnancies. Levels of both HPL and P were significantly higher in duplex than in simplex pregnancies. However, this was not the case for E2. There was a significant correlation between HPL and P levels. It is indicated that measurement of plasma P levels, as those of HPL levels, but not E2 levels is of value for detecting twin pregnancy.

Adult↗
PubMed1978

Studies on calcium uptake by myometrial microsomes with particular reference to the dependence on inorganic phosphate and oxalate.

Ca uptake by microsomes isolated from non-pregnant rabbit myometrium was potentiated by both inorganic phosphate (Pi) and oxalate anions. Both Pi and oxalate had little effect on the initial rate of uptake but a pronounced effect on the capacity of Ca uptake measured after 20 min which was greater in the presence of oxalate than that of Pi (5 mM each). The presence or absence of sucrose in the uptake medium had a significant effect on oxalate-induced potentiation of Ca uptake but not on that potentiated by Pi or that measured in the absence of either potentiating anion. A part of Ca accumulated additionally under the influence of sucrose could be removed by washing microsomes with KCl. Another significant difference between the pontentiating effect of oxalate and Pi was observed when the pH of the incubation medium was varied. In the presence of oxalate the pH optimum was between 6.4--6.8, whereas that in its absence or in the presence of Pi the optimal pH was around 7.2. Reduction in pH from 7.2 to 6.8 along with the substitution of KCl by sucrose resulted in 3-fold increase in Ca uptake when oxalate was used as the potentiating anion. The results suggest that Ca is taken up by a different mechanism in the presence of oxalate than that in its absence or when oxalate anion is substituted with inorganic phosphate.

Animals↗
PubMed1978

Effects of diethylstilboestrol and ovarian steroids on the contractile responses and calcium movements in rat uterine smooth muscle.

1. The synthetic oestrogen diethylstilboestrol had a potent inhibitory effect on the mechanical responses of the rat uterus. The spontaneous contractions were reduced in amplitude by 2 microgram and were completely abolished by 20 microgram diethylstilboestrol. The amplitude of contractions induced by acetylcholine (ACh) was also considerably reduced in the presence of 20 microgram of the compound. 2. Oestradiol (oestradiol-17 beta) had a weaker, and progesterone a negligible, effect on the spontaneous contractions. 3. In the depolarized (induced by high potassium) uterus, the log concentration response curve for contraction induced by Ca was sigmoidal and reached its maximum at about 1 mM-Ca. These responses to Ca were greatly depressed by oestradiol and progesterone and were again completely abolished by diethylstilboestrol. All three compounds were also able to induce a relatively rapid relaxation in preparations contracted by Ca. 4. Inhibition of the ACh contraction in the depolarized uterus by diethylstilboestrol, oestradiol and progesterone had the characteristic of blocking the second, and relatively slow, phase of the contraction without influencing the first rapid response. A similar pattern of inhibition was observed in the presence of D-600 or EGTA. 5. The lanthanum method gave only an approximate measure of cellular Ca in the rat uterus, since La failed to block 45Ca efflux and was unable effectively to displace extracellular 45Ca. 6. Diethylstilboestrol reduced the influx of 45Ca both in normal and depolarizing media but did not affect 45Ca efflux. 7. These results indicate that oestrogens and progesterone are able to decrease Ca entry into the uterine cells, which probably accounts for their inhibitory effect on the contractile activity. The mechanism by which these agents induce relaxation of a contracted uterus also seems to depend on the inhibition of Ca influx.

Acetylcholine↗
PubMed1978

Estrogen and progesterone interactions in the rabbit uterus in vivo after steroid administration.

After a single injection of Estradurin (polyestradiolphosphate), rabbit plasma 17 beta-estradiol (E2) levels rose to a maximum in 3 days and were maintained for at least a 13-day period. The uterine E2 concentration rose slowly so that at day 12 the tissue/plasma E2 ratio was similar to that in untreated controls. The gain in tissue weight after the Estradurin injection correlated well with the increase in tissue E2 concentration. In a group of rabbits to which progesterone (P) was administered 7 days after Estradurin injection, the E2 concentration in plasma did not change significantly. However, the tissue E2 concentration showed a significant decrease after four daily injections of P. When P injections were halted (progesterone withdrawal) for 2 days, the tissue E2 levels rose and were greater than those found in the group not receiving P. These levels were significantly higher than those found in animals which had received daily injections of P for 2 or 4 days. These results indicate that P is able to suppress the accumulation of E2 by uterine tissue, in agreement with published evidence that P is able to reduce the levels of cytoplasmic E2 receptors.

Animals↗
PubMed1978

17 beta-Estradiol and progesterone concentrations in myometrium of pregnancy and their relationships to concentrations in peripheral plasma.

17 beta-Estradiol (E2) and progesterone (P) concentrations in blood and in the myometrium of human pregnancy at term (n=33) and in a few samples (n=5) around midterm of pregnancy were determined. E2 concentration in the myometrium (per g wet wt) at midterm was lower than the concentration in the plasma (per ml) so that the myometrium to plasma (My:Pl) ratio was 0.7. Relative to plasma concentration, the myometrial E2 increased little from midterm to term so that My:Pl was only 0.2 at term. Although P concentration in the myometrium was much greater than that in the plasma at midterm, My:Pl ratio being 2.2, it was lower than that in plasma at term so that My:Pl ratio was only 0.6. A fairly good correlation between plasma steroids and the myometrial steroids was observed at midterm but was distorted at term, probably due to saturation of the tissue-binding capacity. Steroid concentrations determined on the basis of protein showed a good correlation to the values expressed on the basis of wet weight. Whereas myometrial E2 concentration was significantly influenced by the distance from placenta, P concentration was not.

Estradiol↗
PubMed1977

A comparative study of the calcium accumulation by mitochondria and microsomes isolated from the smooth muscle of the guinea-pig taenia coli.

The calcium uptake by mitochondria and microsomes isolated from the guinea-pig taenia coli was studied at physiological Ca2+ concentrations, buffered by Ca-EGTA mixtures. The Ca accumulation by the mitochondria was measured from the difference between the amount of Ca taken up in the presence and in the absence of a specific mitochondrial inhibitor. The Ca uptake by the microsomes was determined in a solution containing oxalate and a mitochondrial inhibitor. It was calculated from the difference in Ca uptake measured with and without ATP. By using this procedure, the necessity of extensive purification of the isolated fractions was avoided. The (Ca2+) for half-maximal transport in the mitochondria is 7 X 10(-6) M. At (Ca2+) lower than 2 X 10(-7) M, Ca is taken up in an energy-dependent way. In the microsomes the apparent Km for Ca is 7 X 10(-7) m. accumulation is still stimulated by ATP at a (Ca2+) as low as 4 X 10(-8) M. The results show that the rate of Ca uptake by the cell organelles corresponding to the microsomal vesicles is sufficiently fast to explain the speed of relaxation of the taenia coli. The results also suggest that these cell organelles are more important than the mitochondria in regulating the cytoplasmic Ca concentration.

Adenosine Triphosphate↗
PubMed1977

Differences in the effects of vasopressin and oxytocin on rabbit myometrial activity and a possible mediation of prostaglandins.

Uterine responses to vasopressin and oxytocin were monitored in non-pregnant and 3- or 6-8-day-pregnant rabbits by recording the intrauterine pressure. Oxytocin stimulated uterine activity in all groups, but the effect of vasopressin was stimulatory in non-pregnant animals, inhibitory in those 3 days post coitum and weakly stimulatory in those later in pregnancy. Inhibition of prostaglandin (PG) synthesis, by the administration of indomethacin, reduced the spontaneous uterine activity as well as the responses to oxytocin and vasopressin in the non-pregnant rabbits, but had little effect in the pregnant animals. During infusion of PGF-2alpha, PGE-1 or PGE-2 in 6-8-day-pregnant rabbits, the stimulatory response to vasopressin, although slight before the infusion, was inhibited whereas the stimulatory response to oxytocin remained virtually unchanged. The results suggest that vasopressin and oxytocin under certain hormonal conditions, are able to activated the uterine contractions by mechanisms in which the involvement of PG is not obligatory.

Animals↗
PubMed1977

Effect of betamethasone administration on estrone, estradiol-17 beta, and progesterone in maternal plasma and amniotic fluid.

As part of a series of studies on the endocrine consequences of corticosteroid treatment during late pregnancy, the levels of unconjugated estrone (E1), estradiol-14 beta (E2), and progesterone were followed in maternal plasma and amniotic fluid before and after treatment. Ten gravidas in the 30th-35th gestational week received 12 mg betamethasone daily for 3 days for prevention of idiopathic respiratory distress syndrome (IRDS) and were compared to 5 controls. The steroid concentrations were determined by radioimmunoassay. The plasma levels of E1 and E2 were depressed to 38% and 29%, respectively, while that of progesterone was not affected. No significant change of the steroid concentrations in amniotic fluid was observed. The decreased E2: progesterone ratio in maternal blood after betamethasone treatment in the human is in contrast to the increased ratio observed in ruminants after corticosteroid administration and preceding the spontaneous onset of labor. The fall in the E2: progesterone ratio accords with the earlier observed inability of intramuscular corticosteroid treatment of elicit labor in women at this stage of gestation. The earlier demonstrated marked depression of cortisol in fetal plasma after betamethasone seems paradoxical in view of the seemingly high availability of progesterone, considered as a precursor for the cortisol biosynthesis in the human fetal adrenal cortex.

Amniotic Fluid↗
PubMed1976

Mechanism for increased production of prostaglandins in labour.

It is proposed that uterine hypoxia, beginning initially with the uterine contractions in late pregnancy, leads to the increased formation of free fatty acids. The liberated fatty acids are then used to form prostaglandins and they can also act on mitochondria to release calcium. The released calcium can directly activate contractile proteins and/or can further stimulate phospholipase A (active at neutral pH) and thereby reinforce the progressive production of prostaglandins.

Calcium↗