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PubMed1999

Blood feeding and oviposition by Culex nigripalpus (Diptera: Culicidae) before, during, and after a widespread St. Louis encephalitis virus epidemic in Florida.

A widespread epidemic of St. Louis encephalitis (SLE) virus was reported from central Florida from late July through December 1990 with 226 clinical cases and 11 deaths in humans. The abundance of blood-fed and gravid Culex nigripalpus Theobald females, the vector of SLE in Florida, was monitored at a resting site in Indian River County, FL, for the 3 yr before the epidemic, the epidemic year, and for 1 yr following the epidemic. Each study year was divided into four 3-mo periods that depict the subtropical SLE transmission cycle; a January-March maintenance phase, an April-June amplification phase, a July-September early transmission phase, and an October-December late transmission phase. The abundance of blood-fed and gravid females was significantly greater during the amplification, early transmission, and late transmission phases of the 1990 SLE epidemic when compared with the 3 pre-epidemic years. Throughout the study, Cx. nigripalpus blood feeding and oviposition was driven by epic (> 50 mm) rainfall events. The abundance of gravid females decreased, whereas the number of blood-fed females increased following heavy rainfalls. Epizootic and epidemic transmission of SLE to sentinel chickens and humans in Indian River County was greatest immediately following heavy rainfalls that synchronized Cx. nigripalpus oviposition and blood feeding.

Animals↗
PubMed1999

Sugar feeding by Culicoides mississippiensis (Diptera: Ceratopogonidae) on the yaupon holly, Ilex vomitoria.

Adult Culicoides mississippiensis Hoffman were collected from 5 flowering yaupon holly plants at sunrise, late morning, early afternoon, and sunset from 5 flowering yaupon holly plants during the entire flowering season (16 March-15 April 1995). Individual insects were tested for fructose by using the cold anthrone test. Prevalence of fructose in C. mississippiensis was 55.6% (427 of 768), with positivity for gravid females greater than for males. Fructose positive rates decreased in gravid females from morning to evening, whereas male rates were constant until evening, when they decreased. Both sugar feeding by gravid females and host-seeking by parous females were highest at sunset, followed by sunrise.

Animals↗
PubMed2001

Evaluation of the developmental toxicity of isoeugenol in Sprague-Dawley (CD) rats.

Isoeugenol, used as a perfumery and flavoring agent, was evaluated for developmental toxicity. Timed-pregnant CD((R)) outbred albino Sprague-Dawley rats received isoeugenol (250, 500, or 1000 mg/kg/day) or vehicle (5 ml/kg corn oil) by gavage on gestational days (gd) 6 through 19. Maternal food and water consumption, body weight, and clinical signs were monitored at regular intervals throughout gestation. At termination (gd 20), confirmed-pregnant females (23-25 per group) were evaluated for gestational outcome. All live fetuses were weighed and examined for external malformations, and approximately 50% were evaluated for visceral or skeletal malformations. There were no treatment-related maternal deaths. Clinical signs associated with isoeugenol exposure included dose-related evidence of sedation and aversion to treatment (rooting behavior) in all isoeugenol groups, as well as an increased incidence of piloerection at >/= 500 mg/kg/day. Maternal body weight, weight gain, and gestational weight gain (corrected for gravid uterine weight) were reduced at all doses in a dose-related manner. Gravid uterine weight was significantly decreased at the mid and high doses, whereas maternal relative liver weight was increased at all three dose levels. During treatment (gd 6 to 20), maternal relative food consumption was significantly decreased at the high dose, and maternal relative water consumption was elevated in the mid- and high-dose groups. Prenatal mortality (resorption or late fetal death) was unaffected. At 1000 mg/kg/day, average fetal body weight/litter was decreased by 7% (male) or 9% (female). Incidences of fetal morphological anomalies were statistically equivalent among groups, except for an increase in the incidence of unossified sternebra(e), a skeletal variation, at the high dose. In summary, the maternal toxicity lowest observed adverse effect level (LOAEL) was 250 mg/kg/day based primarily on reduced body weight and gestational weight gain (corrected for gravid uterine weight), and the maternal toxicity no observed adverse effect level (NOAEL) was not determined in this study. The developmental toxicity LOAEL was 1000 mg/kg/day based on intrauterine growth retardation and mildly delayed skeletal ossification. The developmental toxicity NOAEL was 500 mg/kg/day.

Abnormalities, Drug-Induced↗
PubMed1983

Effects of the embryo upon endometrial estrogen synthesis in the rabbit.

To analyze for the possible embryonic effects upon endometrial estrogen synthesis (estrone, estradiol, estrone sulfate and estradiol sulfate), endometrial samples from each horn of unilaterally tubal-ligated estrous, pseudopregnant and pregnant rabbits were incubated with [3H] progesterone or [3H] androstenedione on Days 0, and 3 to 8 postcoitum. No endometrial estrogen synthesis was detected on Day 0, or on Days 3 to 5 of pseudopregnancy but low levels of estrogens (less than 0.7 pg/g wet wt) were detectable from androstenedione metabolism when individual samples were pooled (n=4 per day) for Days 6, 7 and 8 of pseudopregnancy. Low levels of estrogen synthesized from the pseudopregnant endometrium may represent a latent capability without the required stimulation for active synthesis. In pregnant animals, incubation of the gravid horn endometrium with either substrate produced similar trends of estrogen synthesis, in that estrogen levels increased at Days 4 to 5 (P less than 0.01), stabilized until Day 7 when levels decreased and then further increased on Day 8 (P less than 0.05). Estrogen synthesis by the endometrium of the nongravid horn was generally lower (P less than 0.05) than the gravid horn and stabilized or decreased as pregnancy progressed. Increased estrogen synthesis by the endometrium from pregnant rabbits and particularly from the gravid horn denotes a possible relationship between the developing embryo and endometrial estrogen synthesis.

Androstenedione↗
PubMed1985

Inhibition of postpartum uterine involution in the rat by relaxin.

The possible contribution of relaxin to the support of uterine accommodation during late gestation by retarding tissue lysis was examined using the involuting postpartum uteri of unilaterally pregnant rats. In otherwise intact animals, twice-daily administration of 0.1 mg of relaxin (porcine fraction B) significantly retarded the regression of both gravid and, to a greater extent, nongravid tissue during the first 4 days postpartum, and collagenolysis was similarly delayed. Immediate postpartum ovariectomy had little effect on the uterus, although 5 micrograms estradiol benzoate daily suppressed uterine involution in the gravid tissue to about 50% and was even more effective in the nongravid uterus. Relaxin alone had little effect on the gravid uterus following ovariectomy, but augmented estrogen to the extent that less than half of the tissue and its collagen were lost during 4 days. The effect on nongravid tissue was even more striking in that the combination of estrogen and relaxin prevented any degradation of tissue in general or of collagen. Although we have reported that relaxin can stimulate uterine collagen synthesis as well as uterine growth, the magnitude of its postpartum effect in the presence of estrogen suggests a stabilizing or anticatabolic effect upon the uterus.

Animals↗
PubMed1992

Growth and microvascular development of the uterus during early pregnancy in ewes.

Growth and microvascular development of the uterus were evaluated for ewes on Days 12, 18, 24, and 30 after mating (3-4 ewes/day; Day 0 = day of mating) in two experiments. In experiment 1, fresh weight and dry weight of gravid uterine horns were increased on Days 24 and 30 after mating, whereas those of nongravid uterine horns were elevated only on Day 30. The increased fresh and dry weights of gravid uterine horns on Day 24 were associated with uterine hyperplasia (increased DNA content). Increased fresh and dry weights of gravid uterine horns on Day 30, however, were associated with hypertrophy (increased RNA:DNA and protein:DNA ratios) of uterine tissues. In experiment 2, vascularity of endometrial tissues was elevated on Days 24 and 30 after mating. In addition, dramatic changes in uterine architecture (increased lumenal diameter and decreased endometrial thickness) and in uterine microvascular development (increased abundance of large microvessels and development of a subepithelial capillary plexus) were observed by Day 24 after mating. Characterization of the patterns of uterine growth and microvascular development will enable us to further define the role of previously reported uterine and conceptus-derived growth and angiogenic factors during early pregnancy.

Animals↗
PubMed2002

Effect of the regressing corpus luteum of pregnancy on ovarian folliculogenesis after parturition in cattle.

In cattle, the first postpartum dominant follicle has a predilection for the ovary contralateral to the previously gravid uterine horn, possibly due to a local inhibitory effect of the regressing corpus luteum of pregnancy in the ipsilateral ovary. The aim of the present study was to test the hypothesis that the regressing corpus luteum of pregnancy suppresses folliculogenesis in the ipsilateral ovary after parturition. Dairy cows were treated with prostaglandin F2alpha between 190 and 220 days of gestation to cause luteolysis without inducing parturition (n = 14) or were untreated controls (n = 32). Follicular growth and function were monitored by daily transrectal ultrasonography and collection of plasma samples for estimation of FSH, estradiol, and progesterone concentrations. The proportion of first dominant follicles in the ipsilateral ovary was similar for treated and control animals (4/14 vs. 8/32), as was the time interval between calving and establishment of a dominant follicle (mean +/- SEM, 10.1 +/- 0.4 vs. 10.7 +/- 0.5 days). Furthermore, no significant effect of treatment on dominant follicle growth or function was found as determined by plasma hormone concentrations. Although greater folliculogenesis was found in the ovary contralateral to the previously gravid uterine horn, once the location of the future first dominant follicle was selected, the timing of events was independent of location. We suggest that the corpus luteum of pregnancy does not have a local effect on postpartum ovarian folliculogenesis and that, instead, an effect of the previously gravid uterine horn shortly after parturition should be considered.

Animals↗
PubMed2002

Up-regulation of mesotocin receptors in the tammar wallaby myometrium is pregnancy-specific and independent of estrogen.

The oxytocin-like peptide of most Australian marsupials is mesotocin, which stimulates uterine contractions and is important for normal birth in the tammar wallaby. Female marsupials have two uteri and, in monovular species such as the tammar, one uterus is gravid with a single fetus, whereas the contralateral uterus is nongravid. A significant increase in myometrial mesotocin receptor concentrations occurs only in the gravid uterus on Day 23 of the 26-day gestation. This study examined whether or not mesotocin receptors are present in the myometrium and are up-regulated at the equivalent stage of the luteal phase in unmated tammars. In contrast to the marked increase in mesotocin receptor mRNA and protein concentrations in the myometrium of the gravid uterus during pregnancy, receptors did not increase in the unmated animals. There were also no significant differences between the two uteri, except on Day 27. Plasma profiles of peripheral estradiol-17beta and progesterone did not differ significantly between pregnant and nonpregnant cycles. However, progesterone concentrations were significantly lower on Day 1 postpartum compared with Day 27 of the nonpregnant cycle. In pregnant tammars, the molar ratio of circulating estradiol-17beta to progesterone increased significantly between Day 25 of gestation and 1 day postpartum, but was not correlated with an increase in mesotocin receptor concentrations in either uterus. The data confirm that a local fetal influence is more important than systemic factors, such as estrogen, in the regulation of uterine mesotocin receptors in the tammar wallaby.

Animals↗
PubMed1987

The effect of ephedrine upon uterine artery blood flow velocity in the pregnant guinea pig subjected to terbutaline infusion and acute hemorrhage.

The purpose of the present study was to determine the effect of intravenously administered ephedrine upon uterine artery blood flow velocity (UBFV) in the gravid guinea pig subjected to terbutaline infusion and acute hemorrhage. Ephedrine, 1.0 mg/kg, was administered intravenously to ten chronically instrumented pregnant guinea pigs near term, before and after intravenous infusion of terbutaline and acute hemorrhage. Before terbutaline and hemorrhage, ephedrine increased maternal mean arterial pressure (MMAP) by 30 +/- 1% (P = .0001) and 17 +/- 1% (P = .0001) at 30 s and at 1 min after injection, respectively; UBFV was decreased by 10 +/- 4% (P less than .01) and 14 +/- 4% (P less than .01) at 1 min and at 90 s after injection, respectively. Infusion of terbutaline (1.5-6.0 ug X kg-1 X min-1) increased maternal heart rate (MHR) by 22 +/- 1% (P = .0001), decreased MMAP by 13 +/- 2% (P = .0001), and decreased UBFV by 24 +/- 3% (P = .0001). During hypotension resulting from acute hemorrhage, ephedrine, 1.0 mg/kg, was superior to placebo in restoring MMAP and UBFV toward the prebleed values. The authors concluded that ephedrine, 1.0 mg/kg, results in a small, transient decrease in UBFV in the normotensive gravid guinea pig. However, ephedrine aids restoration of UBFV in the gravid guinea pig rendered hypotensive by acute hemorrhage during terbutaline infusion.

Animals↗
PubMed1992

Which vasopressor should be used to treat hypotension during magnesium sulfate infusion and epidural anesthesia?

Ephedrine restores and/or protects uterine blood flow and fetal well-being in laboratory animals. In contrast, alpha 1-adrenergic agonists worsen uterine blood flow and fetal condition. We previously demonstrated that magnesium sulfate (MgSO4) attenuates the detrimental effects of phenylephrine on uterine vascular resistance in gravid ewes. Therefore, we performed this study to determine whether ephedrine or phenylephrine better restores and protects uterine blood flow and fetal oxygenation during epidural anesthesia-induced hypotension in hypermagnesemic gravid ewes. Twelve chronically instrumented gravid ewes were each used for three experiments: 1) ephedrine, 2) phenylephrine, and 3) normal saline (NS)-control. For each experiment the protocol was as follows: 1) at time zero, intravenous infusion of MgSO4 was begun; 2) at 150 min a thoracic level of epidural anesthesia was achieved with 2% lidocaine; and 3) at 165 min, an intravenous infusion of ephedrine, phenylephrine, or NS was begun and continued through 195 min. Epidural anesthesia uniformly decreased maternal mean arterial blood pressure (MAP), heart rate, cardiac output, uterine blood flow, and fetal PO2 in each of the three groups. Both ephedrine and phenylephrine restored maternal MAP to baseline, as expected from the experimental design. Ephedrine significantly increased cardiac output and uterine blood flow when compared with NS-control, but phenylephrine did not. Phenylephrine significantly increased uterine vascular resistance when compared with NS-control, but ephedrine did not. As a result, fetal pH and PO2 were significantly greater during ephedrine infusion than during infusion of NS-control. Fetal pH was stable during ephedrine infusion, but it continued to decrease during phenylephrine infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Epidural↗
PubMed1994

Ephedrine remains the vasopressor of choice for treatment of hypotension during ritodrine infusion and epidural anesthesia.

BACKGROUND: Historically, ephedrine has been the vasopressor of choice for treatment of most cases of hypotension in obstetric patients. However, the choice of vasopressor in the parturient receiving a beta-adrenergic agent for tocolysis has not been evaluated extensively. The current study evaluated whether ephedrine or phenylephrine better restores uterine blood flow and fetal oxygenation during ritodrine infusion and epidural anesthesia-induced hypotension in gravid ewes. METHODS: Fourteen chronically instrumented gravid ewes between 0.8 and 0.9 timed gestational age were used. On separate days, each animal underwent the experimental protocol with one of three agents: ephedrine, phenylephrine, and normal saline-control. The experimental protocol was as follows: (1) at time zero, intravenous infusion of ritodrine was begun; (2) at 120 min, 2% lidocaine was given epidurally to achieve a sensory level of at least T6; and (3) at 135 min, an intravenous bolus of either ephedrine, phenylephrine, or normal saline-control was given, followed by a continuous intravenous infusion of the same agent for 30 min. In the ephedrine and phenylephrine experiments, the rate of infusion was adjusted to maintain maternal mean arterial pressure close to baseline. RESULTS: Ritodrine infusion alone significantly increased maternal heart rate and cardiac output in all three groups. Epidural anesthesia during ritodrine infusion significantly decreased maternal mean arterial pressure, heart rate, cardiac output, uterine blood flow, and fetal arterial oxygen tension for each of the three groups. Both ephedrine and phenylephrine restored maternal mean arterial pressure to baseline, as designed. Ephedrine significantly increased uterine blood flow and fetal arterial oxygen tension when compared with normal saline--control, but phenylephrine did not. Phenylephrine significantly increased uterine vascular resistance when compared with normal saline--control, but ephedrine did not. CONCLUSIONS: Although ephedrine and phenylephrine provided similar restoration of maternal mean arterial pressure, ephedrine was superior to phenylephrine in restoring uterine blood flow during ritodrine infusion and epidural anesthesia-induced hypotension in gravid ewes. Also, ephedrine, but not phenylephrine, significantly improved fetal oxygenation, when compared to normal saline--control.

Acid-Base Equilibrium↗
PubMed1997

Prevalence of Chlamydia trachomatis infection in a low-risk population in Hungary.

BACKGROUND AND OBJECTIVE: Chlamydia trachomatis is the leading cause of nongonococcal urethritis and cervicitis in women. Because of the recent increases in the numbers of new cases and severe consequences, there is an urgent demand for the introduction of sensitive and specific rapid diagnostic methods. GOAL: A multicenter examination involving seven centers was sponsored by the Hungarian Ministry of Health and Welfare in order to provide a survey of Chlamydia trachomatis in the gravid population. 6,161 women were tested between 1994 to 1995. STUDY DESIGN: The seven centers were selected with regard to different aspects, from developed and less developed areas in the capital, two large provincial towns, and various other provincial regions reflecting either an industrial or an agricultural background. The nucleic acid hybridization method (PACE 2 Gen-Probe, San Diego, CA) was introduced in this low-risk population for the examination of Chlamydia trachomatis. In one center, a further two methods, antigen detection by ELISA (SYVA, CA) and cultivation on the McCoy cell line (staining with SYVA FITC-labeled antichlamydia monoclonal antibody), were applied. RESULTS: International surveys and experience indicate that the proportion of the population threatened by Chlamydia trachomatis is above 10%. The overall average incidence of Chlamydia trachomatis cases in this low-risk gravid population was 5.74%. The data from the different centers ranged between 1.6% and 9.7%. The chlamydia-infected Hungarian gravid population is below the critical 10%, but there is one Hungarian county where the value is close to 10%. CONCLUSIONS: In this provincial, industrial area, the number of unmarried and divorced gravida in a low economic situation is disproportionately high. For this disadvantaged population, permanent Chlamydia trachomatis screening was suggested. In the other centers, screening of pregnant women for Chlamydia trachomatis and the treatment of positive cases and their partners were suggested for pathological gravida with preterm labor and preterm rupture of the membranes.

Adult↗
PubMed1997

The gecko: an environmentally friendly biological agent for mosquito control.

Laboratory experiments with Aedes aegypti mosquitoes investigated the effects of light, mosquito density and physiological state on predation rates by the Australian gecko Gehydra dubia and the exotic Asian house gecko Hemidactylus frenatus. For both gecko species a positive correlation was demonstrated between prey density and the predation rate. Using Ae.aegypti males and unfed females as prey in a terrarium (0.054 m3), consumption rates reached 76-108/day for G.dubia and 63-109/day for H.frenatus, with significantly more female mosquitoes than males being eaten in most experiments. Comparing dark with semi-illuminated conditions no consistent contrast of predation rate was demonstrated. Gehyra dubia predation rates on various Australian mosquito species were compared in an experimental room (32 m3) for 24 h exposure with photoperiod L:D 12:12 h Five photophilic species (Aedes vigilax, Anopheles annulipes, Coquillettidia xanthogaster, Culex annulirostris, Cx sitiens) suffered 78-100% predation, compared with only 33-53% predation of four non-photophilic species: Aedes aegypti, Ae.notoscriptus, Ae.vittiger and Cx quinquefasciatus. This demonstrates the potential benefit of domestication for geckoes that learn to hunt at light. When offered a mixture of unfed, freshly blood-fed and gravid females of Ae.aegypti in an illuminated terrarium, both gecko species consumed significantly more unfed than fed or gravid female mosquitoes, presumably because the latter rested whereas the former foraged more actively. H.frenatus consumed significantly more mosquitoes of all categories than did G.dubia per 24 h: unfeds 5.1 +/- 0.1% v. 4.5 +/- 0.5%, blood-feds 4.5 +/- 0.3% v. 4.0 +/- 0.5% and gravids 4.8 +/- 0.4% v. 3.9 +/- 0.5%. Possible relevance of these results to competitive displacement of G.dubia by H.frenatus is discussed.

Aedes↗
PubMed2006

Evisceration of pregnant uterus through the incisional hernia site.

The herniation of a gravid uterus through an incisional hernia site is a rare occurrence, but the evisceration of the gravid uterus through the incisional hernia is even rarer. The following is a case report of an evisceration of gravid uterus through an incisional hernia of a midline incision.

Adult↗
PubMed1992

A field study of patterns of unobserved foetal loss as determined by rectal palpation in foaling, barren and maiden thoroughbred mares.

Records of 1,009 pregnancies in 574 foaling, barren and maiden Thoroughbred mares on a single stud farm, over a period of 12 years were examined. The farm is situated in the eastern Cape Province of South Africa, at an elevation of 1,800 m, and in an area of climatic extremes. Records of 604 pregnancies in 249 foaling Thoroughbred mares were examined. For these purposes, those pregnancies in which a mare conceived in the same breeding season during which she had foaled were considered as pregnancies in foaling mares. Pregnancy was confirmed by rectal palpation by a single experienced practitioner. Of the 604 pregnancies examined, conceptus attachment occurred in the horn opposite the previously gravid horn in 345 cases (57%), and in the previously gravid horn in 259 cases (43%; P less than 0.005). Unobserved foetal loss after pregnancy diagnosis amounted to 30 (9%) in the former group, while in the latter group (pregnancy established in the postgravid horn) 46 pregnancies were lost (18%; P less than 0.005). This study confirmed that conceptus attachment tends to occur in the uterine horn opposite the previously gravid horn in foaling Thoroughbred mares conceiving during the same season. A significantly higher incidence of foetal loss accompanied conceptus attachment in the postgravid horn. Of 242 pregnancies in 162 previously barren mares, 95 (39%) occurred in the left uterine horn and 147 (61%) in the right horn (P less than 0.005). The incidence of pregnancy failure in this group was 7%. The side of attachment did not affect the rate of loss. Evaluation of the records of 163 maiden mares revealed that conceptus attachment occurred in the left uterine horn in 58 (36%) pregnancies and in the right horn in 105 (64%) pregnancies (P less than 0.005), which is consistent with previously reported observations. Pregnancy failure was recorded in 4% of maiden mares. Side of attachment did not influence rate of loss in this group.

Animals↗
PubMed1992

Systemic hemodynamics and oxygen transport during pregnancy in chronically instrumented, conscious rats.

Knowledge about possible alterations in cardiac output (CO), total peripheral vascular resistance (TPVR), and their time course and magnitude of change is conspicuously lacking for the conscious gravid rat. Therefore, we assessed CO using Fick methodology in unrestrained, chronically instrumented, conscious rats. The rats were studied during early (day 7), mid (day 13), or late gestation (day 18) along with nonpregnant control rats matched with respect to age and days postsurgery. Significant differences between pregnant and nonpregnant rats were observed during midgestation, when CO was increased by 26 +/- 12% and TPVR was decreased by 23 +/- 9% in the pregnant animals. These changes were accompanied by a narrowed arterial-mixed venous oxygen content difference (AVD; P < 0.05 vs. nonpregnant). In late gravid rats, CO was higher than nonpregnant values by 49 +/- 8%, and TPVR was lower by 34 +/- 7% (both P < 0.05). Oxygen consumption and carbon dioxide production were significantly increased, and AVD further narrowed when compared with the nonpregnant control group. With the exception of absent chronic respiratory alkalosis in pregnant rats, we conclude that cardiovascular and respiratory changes in conscious, gravid rats and in pregnant women are comparable. We speculate that the ultimate purpose of many of these adaptations is to increase CO so that oxygen delivery and the supply of nutrients to the uteroplacental units are sufficient or more than sufficient to meet oxygen and nutrient demands. At midgestation, the rise in CO seems to anticipate the oxygen needs of the nascent uteroplacental units.

Animals↗
PubMed1985

Osmoregulation and vasopressin secretion during pregnancy in Brattleboro rats.

Osmoregulation during pregnancy was compared in Brattleboro rats completely lacking vasopressin [homozygous (DI)], those with partial deficiency [heterozygous (HZ)], and control Long-Evans (LE) animals. Plasma osmolality (Posmol) was decreased 10-16 mosmol/kg near term in each group, whereas urine osmolality (Uosmol) was similar to that of virgin controls. This was accompanied by significant increments in water turnover similar in HZ and LE and massive in the gravid DI. Chronic vasopressin treatment increased Uosmol less in pregnant DI compared with virgins (P less than 0.001), and urinary prostaglandin E2 was increased in all gravid groups. Captopril per os failed to implicate the renin-angiotensin system in the altered water ingestive behavior of pregnancy. Basal arginine vasopressin pressure (PAVP) was similar in gravid and virgin HZ and LE, whereas the osmotic threshold for AVP secretion was lower in both pregnant groups. Increasing Posmol by dehydration or hypertonic saline led to similar increments in plasma AVP (PAVP) in pregnant and nongravid rats of each group, but sensitivity of the system delta P AVP/delta P osmol was significantly lower in HZ, a difference compatible with the decreased pituitary AVP content in the HZ strain. Data are consistent with decreases in the osmotic thresholds for AVP release (in HZ and LE) and thirst (in DI) and a need for increased AVP secretion during pregnancy.

Animals↗
PubMed1987

Renal synthesis and urinary excretion of eicosanoids during pregnancy in rats.

We tested whether vasodilatory prostaglandins (PGs) mediate the adaptation of the maternal renal circulation to pregnancy by assessing production of PGs by kidney tissues in vitro. We reasoned that if PGs are crucial, then local synthetic rates of these hormones would most likely be increased. Glomeruli harvested from gravid rats of gestational days 6, 12, and 20 did not demonstrate greater basal or stimulated syntheses of PGF2 alpha, PGE2, or 6-keto-PGF1 alpha than those from virgin controls. Production of PGE2 and 6-keto-PGF1 alpha by renal cortical slices obtained from pregnant rats was not greater than that of virgins either. Urine 24-h excretory rates of PGE2 and 6-keto-PGF1 alpha, but not PGF2 alpha, were significantly increased during pregnancy (all P less than 0.05 from prepregnant levels). During midgestation, when urinary excretion of PGE2 and 6-keto-PGF1 alpha was greatest, medullary syntheses of these PGs were found to be comparable between virgin and gravid animals. The present study, which fails to show augmented synthesis of PGs by renal tissues derived from gravid rats, is consistent with our previous investigation in which cyclooxygenase inhibition did not reduce the gestational increase of renal hemodynamics or restore the attenuated renal pressor responsiveness to exogenous angiotensin II. Taken together, we conclude that in rats, PGs most likely do not mediate the alterations in the renal circulation observed during pregnancy.

6-Ketoprostaglandin F1 alpha↗