Uptake and release of 3H prostaglandins E2 and F2 alpha in uterine strips isolated from ovariectomized rats. Influence of in vitro progesterone.

The accumulation and output of 3H -prostaglandins (PGs), E2 and F2 alpha, into and from uterine strips isolated from ovariectomized rats, either in presence or in absence of exogenous progesterone, were explored. Tissue-to-medium ratio of 3H-counts (T/M-ratio), was determined. The same was done in solutions containing 14C-sucrose.

Triglycerides in isolated rat uterine strips. Influences of glucose deprivation, 2-deoxy-D-glucose, estrogens and exogenous or endogenous prostaglandins E1, E2 and F2 alpha.

Triglyceride (TG) levels in uterine strips isolated from natural estrous, ovariectomized or ovariectomized, estradiol-injected rats, were explored. Determinations were performed either immediately after isolation (initial or 0 time) as well as after one hour period of incubation (60 min time) in glucose containing or in glucose-free solution. The influences of indomethacin alone (5 X 10(-6) M) or of indomethacin plus prostaglandins (PGs) E2, E1 or F2 alpha (10(-7) M).

Biological profile of a bioactive aortic substance (BAS), released by vessel rings from indomethacin-treated rats.

The biological activity of a stable unknown material(s), generated by aortic rings (bioactive aortic substance = BAS) isolated from rats injected with a high dose of indomethacin, was explored on contractions of several smooth muscle preparations from normal rats and its effects compared with those elicited by prostacyclin (PGI2) or by 6-keto-prostaglandin F1 alpha (6-k-PGF1 alpha). The BAS evoked, as did PGI2 or 6-k-PGF1 alpha, positive inotropism in strips from rat stomach, ileum and urinary bladder, but failed to influence uterine contractions as did prostacyclin or its non-enzymatic metabolite. When tested in rat aortic strips both, PGI2 and the BAS produced relaxation, whereas 6-k-PGF1 alpha was not active.

Norepinephrine alters PGE2/PGE1 output ratio in isolated uterus from ovariectomized rats.

The rat uterus generates and releases prostaglandins (PGs) of the series 2 as well as PGs of the series 1. The main purposes of the present study are to compare the effects of norepinephrine (NE) on the production and outputs of PGE1, PGE2 and PGF2 alpha by the uterus isolated from ovariectomized rats, treated or not with 17-beta-estradiol and to explore also, whether the effects of NE on PG synthesis are mediated through alpha, beta or both types of adrenoreceptors. Segments of control uterine horns obtained from ovariectomized rats generated and released into the incubating solution, equal amounts of PGE1, PGE2 and PGF2 alpha and propranolol (10(-6) M) or phentolamine (10(-6) M) failed to alter this basal production of PGs.

Catecholamines in sow graafian follicles at proestrus and at diestrus.

Endogenous dopamine, noradrenaline, and adrenaline were detected in the sow graafian follicular wall and in the follicular fluid. Noradrenaline represented the highest level and adrenaline the lowest. Dopamine and noradrenaline concentrations found in the follicular fluid were lower at early proestrus than at mid-diestrus, whereas adrenaline levels in the fluid did not differ at either stage of the estrous cycle.

Converting enzyme activity in sow oviducts at different stages of the sex cycle. Influence of inhibitors of prostaglandin synthesis and its possible role in the inotropic effects of bradykinin.

The existence of angiotensin I converting enzyme (CE) activity in isolated sow Fallopian tubes and the "in vitro" influences of exogenous bradykinin (BK) on the spontaneous motility of sow oviducts, were explored. Independently of the stage of the sex cycle, the ampullary region of sow Fallopian tubes presented a higher basal CE activity than the isthmic one. On the other hand a greater CE activity was found in the isthmus at estrus and metestrus than at proestrus.

Non-cholinergic inotropic responses evoked by electric field stimulation in the isolated rat urinary bladder. Possible participation of substance P.

The present study explores whether a peptide, such as substance P (SP), has some role subserving the atropine-resistant component of electrically-evoked contractions, in isolated rat urinary bladders. The electric field stimulation (EFS) employed herein, consisted in square wave pulses of 5 Hz, 50 ms duration and supramaximal voltage (40 V), applied for 10 sec, every 3 min and conducted to the tissue via a pair of platinum ring electrodes, surrounding the isolated preparations. In order to assess whether electric stimuli, induced urinary bladder inotropism through the activation of nerve structures, degeneration of intramural nerve elements was attempted by cooling the tissue (48 h at 4-5 degrees C).

Different effects of prostaglandins E2 and F2 alpha on triglyceride levels in uterine smooth muscle from diabetic diestrous rats.

Triglyceride (TG) concentrations in uterine strips isolated from diestrous normal rats, from diestrous streptozotocin (single iv. injection of 65 mg X Kg body weight-1)-diabetic rats and from diestrous diabetic animals, treated in vivo with insulin (protamine zinc insulin 4U X day-1, 6 days, sc.), were measured.

On the inotropic effects of leukotrienes in the isolated urinary bladder of guinea pigs and rats.

Leukotrienes (LTs) B4, C4 and D4 were tested on the motility of rings isolated from the urinary bladder of guinea pigs and rats. LTB4 did not evoke inotropic influences in any of the preparations, whereas LTC4 and LTD4 augmented the magnitudes of tonic and phasic contractions in the guinea pig but not in the rat detrusor muscle, LTC4 evoking a greater enhancement than LTD4. On molar bases, acetylcholine induced smaller positive inotropic effects.

The efflux from and the metabolism of 3H-norepinephrine in sow Graafian follicles. Variable involvement of some prostaglandins during two different stages of the sex cycle.

The influences of acetylsalicylic acid (ASA) and of prostaglandins (PGs) E1, E2 or F2 alpha, on the spontaneous total tritium efflux from and on the metabolism of 3H-norepinephrine (3H-NE) in the walls of sow Graafian follicles isolated during two different stages of the sex cycle, were studied. The total 3H efflux from preparations obtained in proestrus (early preovulatory period) was higher than the output from diestrous tissues. This augmentation observed in proestrous samples, mainly attributable to a greater metabolism of 3H-NE, was expressed by an enhanced 3H-efflux corresponding to 3H-O-methylated (3H-OMDA) and 3H-normetanephrine (3H-NMN) metabolites.

Influence of sex hormones on prostaglandin dehydrogenase activity in the rat uterus.

The present experiments report the effects of estradiol or of progesterone on the activity of 15-prostaglandin-dehydrogenase (PGDH) in the uterus of spayed rats. When the substrate was PGF2 alpha the treatment with progesterone (4 mg X day-1, two days) or with estradiol-17-beta (0.5 ug + 1 ug) did not show any effect on the activity of the enzyme.

Sow (Sus scrofa) follicular fluid: prostaglandin content and effect on the motility of isolated oviducts.

The present study provides information regarding the effects of the sow follicular fluid (FF) on the motility of isolated segments of swine and rabbit oviducts. In addition, the concentration of prostaglandins (PGs) F2 alpha, E2 and E1 in the follicular fluid of sow ovaries isolated at different stages of the sex cycle as well as the generation of the same PGs by walls of ovarian follicles in early and late proestrus, in estrus, in metestrus and in diestrus, were explored. The stimulatory contractile effect of proestrous FF in isolated segments of sow fimbria was antagonized by polyphloretin phosphate (PPP), a PG receptor blocker and by indomethacin, an inhibitor of PG synthesis.

Estradiol -17-beta enhances the formation of (3H)-PGF2 alpha from (3H)-PGE2 in the uterus isolated from ovariectomized rats.

Formation of (3H)-PGF2 alpha and (3H)-13, 14,dihydro-15-keto-PGF2 alpha from (3H)-PGE2 by the supernatant of uterine homogenates from estrous and ovariectomized rats, was studied, using the reaction system PGE2 + NADPH + (3H)-PGE2 + supernatant. Enzymatic conversion was lower in uterine supernatants from spayed rats than in uterine homogenates of rats at natural estrus. Spayed animals were injected with progesterone (P) or with estradiol-17-beta (Eo) at a dose of 1.

The positive inotropic effect of sodium arachidonate on auricles from diabetic rats.

Contractile responses to exogenous sodium arachidonate (NaA) were studied in auricles from normal and acutely diabetic (streptozotocin-treated) rats. NaA induced a concentration-dependent positive inotropic effect in atria from normal and diabetic rats but the magnitude of the contractile influence of the fatty acid was different in both types of auricles, i.e.

On the synthesis of prostaglandins E1, E2 and E2 alpha by sow oviducts. Differential modulation of 1 and 2 series of prostaglandins by norepinephrine.

The present study was performed in order to evaluate whether norepinephrine (NE) can modulate the synthesis and release of 1 and 2 series of prostaglandins (PGs) by the isthmic region of preovulatory sow oviducts and also to clarify whether the action of the neurotransmitter is mediated through alpha, through beta or through both types of tissue adrenoreceptors. NE, at a concentration of 1 microgram/ml, depressed significantly (P less than 0.05) the basal output of PGE1 and enhanced (P less than 0.

Prostaglandins and ovarian factors as modulators of the negative inotropic action of histamine in the isolated rat uterus.

The present study reports findings on: a) the action of histamine (H) on the spontaneous motility of the uterus isolated from rats during four different stages of the sex cycle; b) the relevance of endogenous and exogenous prostaglandins (PGs) for the inotropic effect of H and c) the relationships between these factors and the generation and release of PGs in rat uterine horns obtained during proestrus, estrus, metestrus and diestrus. Cumulative dose-response curves for H, in strips isolated from proestrous rats, showed that the agonist inhibited, at all the concentrations tested, spontaneous myometrial contractions, evoking a maximum effect (100% inhibition) at 10(-5)M. Incubation with acetylsalicylic acid (ASA; 10(-4)M) did not modify the dose-response curve for H.

Prostaglandins and the contractile effect of angiotensin I and II in the uterus isolated from ovariectomized rats. Influences of indomethacin and 17-beta estradiol.

The purpose of the present study was to explore whether, the stimulating contractile action of angiotensin II (AII) or of angiotensin I (AI), in uterine strips isolated from rats, either spayed or spayed and injected with 17-beta estradiol, was somehow linked to tissue generated prostaglandins (PGs). Indomethacin (10(-6)M), shifted to the left the dose-response curve for AII in preparations from ovariectomized animals; augmenting both, the efficacy and the potency of the agonist. Dose-response curves for AII were also explored in the presence of subthreshold concentrations of several exogenous PGs.

Extracellular potassium concentration; perhexiline and SKF-525A on the action of ouabain in isolated self-beating rat auricles.

The influences of different extracellular K+ concentrations and of blockers of potassium and calcium movements through cell membranes (perhexiline and SKF-525A) on the effects of ouabain on self beating isolated rat atria, both "non toxic" (positive inotropism without changes in contractile frequency or resting tension) and "toxic" (positive chronotropism, negative inotropism, contracture, arrhythmia), were explored. Decreasing extracellular K+ from 6 to 3 mM potentiated both the positive inotropic influences as well as the "toxic" effect of ouabain, whereas, increasing K+ from 6 to 8 mM delayed but potentiated the onset of the "non toxic" influences of the drug and abolished its "toxic" responses. Perhexiline and SKF-525A, sensitized the tissue to the "non toxic" effects of the glycoside, attenuated contracture but increased the positive chronotropic action.