Ovarian Blood Flow Rate Research Articles

Ovarian Function and Vascular Resistance After Tubal Sterilization

In this study, 19 women who underwent tubal sterilization with laparoscopic bipolar coagulation were evaluated before the sterilization procedure and 1 year after. Baseline levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol were measured during the early follicular phase (day 3) of the patient's menstrual cycle before tubal sterilization. Ovarian volume, antral follicle counts, and ovarian blood flow rates were determined using transvaginal ultrasonography (TVU). One year after laparoscopy, the hormone measures were repeated, on day 3 of the menstrual cycle, and a repeat TVU was performed. Pre- and postoperative levels of FSH, LH, and estradiol were essentially unchanged. Also, the mean ovarian volume, follicle counts, and ovarian artery resistivity index remained unchanged. When all measurements were compared, ovarian volume and follicle counts were significantly correlated, both before and after sterilization, (P <0.05), and both measures correlated with baseline FSH levels. No other associations were seen.

Effects of unilateral ovariectomy with compensatory hypertrophy on ovarian blood flow, oxygen consumption and progestin secretion in the 16-day pregnant rat.

Stimulated ovulation with resultant multiple corpora lutea (CL) can result in lower progesterone levels than expected from the increased luteal tissue mass. Unilateral ovariectomy (ULO) was used to increase CL number in rats and determine whether this would compromise luteal tissue blood flow, oxygen consumption and progestin secretion. All investigations were performed in vivo, using a venous outflow technique on Day 16 of gestation, when progesterone secretion is maximal. ULO, performed before pregnancy, doubled CL number and total CL mass in the remaining ovary of six treated compared to five control rats. Growth of CL was not affected. The rate of ovarian blood flow (microL min(-1) mg CL(-1)) fell to 47% of control levels in ULO animals and progesterone secretion (microg h(-1) mg CL(-1)) to 68%. Secretion of the minor progestin, 20alpha-hydroxypregn-4-en-one was not affected. Tissue oxygen consumption was maintained despite the reduction in blood flow by an increase in oxygen extraction from arterial blood. These results suggest that overcrowding of CL in ULO-stimulated rat ovaries compromises luteal tissue blood flow and subsequently progesterone secretion.

Neuropeptide Y reduces ovarian blood flow in the rabbit

Neuropeptide Y-containing nerve fibers have previously been demonstrated to innervate the mammalian ovary. These nerve fibers innervate primarily the vasculature. In this study we have developed a method for in vivo measurement of the ovary blood flow rate by means of the 133Xe method. Using this technique we measured the ovary blood flow rate and investigated the dose-response relationship between close intraarterial-injected NPY and the ovary blood flow rate. A monoexponential washout curve for 133Xe was found for the whole washout process, ensuring that the blood flow rate at any time could be calculated from the curve. We found a mean blood flow rate in the nonpregnant rabbit ovary at 43.6±4.4 ml·(100 g) −1· min −1 (mean±SEM). Injection of NPY (20, 200, 2000 pM) in the aorta close to a. ovarica resulted in a dose-dependent decrease in the ovarian blood flow rate with a maximum reduction to 40.7±6.3% (mean±SEM) of the control blood flow rate. These findings make it likely that receptors able to interact with NPY are present in the vasculature of the rabbit ovary.

Evidence for an oscillator other than luteinizing hormone controlling the secretion of progesterone in cattle.

The objective of this study was to quantify and compare the frequencies of pulses in ovarian and systemic concentrations of progesterone, systemic concentrations of luteinizing hormone (LH) and rate of ovarian blood flow. Blood was collected simultaneously from previously implanted catheters in the ovarian venous circulation and jugular vein on Day 12 or 13 of estrous cycles from 4 nonlactating dairy cows. Blood was collected at a rate of 2.5 ml/min for 5 min out of every 10 min over an 8-h period. The mean rate of blood flow in the ovarian artery during the 5-min collection period was estimated by an electromagnetic blood flow transducer. Pulses were observed over time in both ovarian and systemic concentrations of progesterone at frequencies that ranged between 0.625 and 0.875 cycles/h (1.1 to 1.5 h/cycle) among the animals. Only one or two episodes of release of LH were observed during the 8-h period, and transient increases in blood flow to the ovaries were associated temporally with each episode of LH release. The estimated frequencies for release of LH and increased blood flow were the same for each animal and ranged between 0.250 and 0.375 cycles/h. A second cycle with a frequency similar to that for LH was evident in the spectral density functions for ovarian and systemic concentrations of progesterone. This cycle was eliminated when the cycle for LH was removed from the data for progesterone, but the magnitude and frequency of the pulses in progesterone were not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Independence of ovarian progesterone secretion rate from arterial progesterone concentrations in the pregnant rat.

We have sought to determine whether the rate of ovarian progesterone secretion in pregnant rats is inversely related to the arterial plasma progesterone concentrations. For this purpose, rates of ovarian progesterone secretion were measured on day 16 of pregnancy in seven progesterone-treated and eight untreated rats. Treated rats received once-daily s.c. injections of 63.6 mumol progesterone in peanut oil on days 13 to 16. In a separate experiment, this treatment was found to produce a relatively stable fivefold increase in plasma progesterone concentrations. The rate of ovarian blood flow was increased in treated animals (mean +/- S.E.M.; treated, 0.63 +/- 0.08 ml/min; untreated, 0.43 +/- 0.08 ml/min) but the progesterone secretion rate was unchanged (treated, 1.13 +/- 0.20 mumol/day per ovary; untreated, 1.05 +/- 0.15 mumol/day per ovary). The stability of the progesterone secretion rate in the face of a fivefold increase in plasma progesterone concentration implies a lack of negative feedback from progesterone in plasma in the regulation of ovarian progesterone secretion.

Progesterone secretion and ovarian blood flow in the pregnant rat.

A venous outflow technique was used to monitor the rates of ovarian blood flow and progesterone secretion simultaneously during periods of 2-3 h in nine rats pregnant for 16 days and anaesthetized with sodium pentobarbitone. The rate of ovarian blood flow was 0 x 460 +/- 0 x 135 (S.D.) ml/min and that of progesterone secretioin was 27 x 2 +/- 7 x 0 microgram/h per ovary. Within rats, progesterone secretion was unrelated to the rate of ovarian blood flow (common correlation coefficient, r = 0 x 136; degrees of freedom = 61; P, not significant) but the latter was inversely related to the arterio-venous difference in the concentratioin of progesterone (r = --0 x 731; P < 0 x 01).

Effects of an intrauterine device on ovarian secretion of progestagens and oestrogens in pregnant rats: evidence for local effects.

The study attempted to detect any alterations in the secretory pattern of ovarian steroids on Day 4 of pregnancy (day when spermatozoa found in vaginal smear was Day 1) in the presence of a unilateral IUD in the rat. A silk suture was inserted in the lumen along the entire length of 1 uterine horn. The other horn was sham-inserted. Ovarian vein blood was collected either from the IUD side (8) or from the opposite side (8). Each sample was analyzed in duplicate for progesterone 20-alpha-dihydroprogesterone estrone and estradiol by radioimmunoassay. Both the concentration and output of progesterone were significantly (p less than .001 and p less than .01) lower on the IUD than on the opposite side. Concentration and output of 20-alpha-dihydroprogesterone were slightly increased on the IUD side but nonsignificantly (p less than .1). The ratio of progesterone to 20-alpha-dihydroprogesterone concentrations was significantly less (p less than .01) on the IUD side. The decrease in concentration of estradiol on the IUD side was statistically significant (p less than .02) as was the decrease in ratio of estradiol to estrone concentrations. Ovarian blood-flow rates on the 2 sides were comparable. The steroidal effect of the rat IUD may partially account for the local antifertility action. Perhaps the action of the IUD on steroid secretion is mediated through the secretion of pharmacologically active substances such as prostaglandins.

Oxygen Consumption of Embryos and Parents, and Oxygen Transfer Characteristics Within the Ovary of Two Species of Viviparous Seaperch, Rhacochilus vacca and Embiotoca lateralis

Oxygen tension and content of intraovarian fluid were measured for the viviparous pile perch, Rhacochilus vacca, during middle and late gestation. Oxygen tension decreased with increasing demands of the brood, reaching a minimum of 13.7 mm Hg just prior to parturition. Total oxygen content of the ovarian fluid decreased to a minimum of 22 mg O2, rising thereafter to 54 mg O2 at parturition as the volume of ovarian fluid increased. The in vitro oxygen consumption of the young per unit weight increased 2.5 times during gestation reaching 222 mg O2/kg/hr at birth (mean weight 3.8 g).Oxygen consumption of two pregnant striped seaperch, Embiotoca lateralis, was fairly constant at 70 mg O2/kg/hr early in gestation, increasing later to approximately 107 mg O2/kg/hr at parturition.An oxygen dissociation curve was determined for ventricular blood of pregnant pile perch. The p50 was 12.5 mm Hg. Along with other parameters, this was used to estimate the oxygen transfer characteristics of the brood–ovary exchange system, maximum possible oxygen consumption, and ovarian blood flow rate. The capacity of the system to meet the increasing requirements of the young decreased during gestation, reaching limiting conditions at parturition. It was concluded that transfer of oxygen to the young would be controlled by, and ultimately limited by, ovarian blood flow rate. The brood–ovary system is compared with the mammalian placenta.

Short-term ovarian responses to some pituitary hormones infused in vivo in pigs and sheep.

Changes in ovarian function were measured after the administration of hormones in the mid-luteal phase of the estrous cycle in pigs and sheep. Ovarian venous blood was collected for three successive 40-min. or 60-min. periods while saline was infused at a rate approximating the rate of collection. In pigs, for the middle 40-min. period, LH was added to the saline for nine animals and FSH, prolactin and melengestrol acetate were similarly tested. Control animals (six) received only saline during the entire period. LH increased the rate of secretion of progesterone by increasing the concentration of the steroid in plasma while the rate of blood flow remained unchanged. FSH and prolactin also enhanced progesterone production in the two animals receiving each of these hormones. Whether these effects resulted from direct action on the ovary is not known. Melengestrol acetate had no effect. In sheep, during the middle third of the experimental period, LH, FSH, or prolactin was infused into treated animals. LH, tested in 12 ewes, stimulated the rate of progesterone secretion by increasing both the rate of ovarian blood flow and the concentration of steroid in the plasma. FSH produced a similar though less pronounced effect, but only two animals were tested. The one animal that received prolactin behaved like the seven controls. Wide variations between animals were seen in response to similar treatments, but the rate of flow of blood was almost always negatively correlated with the concentration of progesterone in the plasma.

Influence of the pituitary on ovarian progesterone output in the ewe: effects of hypophysectomy and gonadotropic hormones.

A series of experiments was undertaken to determine the acute effects of hypophysectomy and the administration of human chorionic gonadotropin (HCG), ovine luteinizing hormone (LH) and ovine prolactin on progesterone secretion rate in mature reproductively active ewes. Hypophysectomy at midcycle resulted in a highly significant 12-fold decrease below that of either sham-operated or intact animals in the secretion rate of progesterone within 5 hr. This decrease was composed of a 3-fold drop in ovarian venous progesterone concentration and a 4-folddecrease in the rate of ovarian blood flow. Treatment of hypophysectomized animals with 3000 IU HCG, 50 mg LH or 50 mg prolactin resulted in significant increases in ovarian venous progesterone concentration and progesterone secretion rate within 10 to 20 min. It was concluded that the functional activity of the sheep corpus luteum (CL) is regulated by the anterior pituitary, and that both LH and prolactin are capable of stimulating progesterone output. (Endocrino...

Rate of ovarian secretion in the dog.

The average rate of progesterone secretion into the ovarian vein blood of anaestrus dogs under pentobarbital anesthesia, 0.71 μg/ovary/min (range 0.33–1.20), did not significantly change over a 4-hour period following a single I.V. injection of 1000 units of human chorionic gonadotrophin (HCG). I.M. administration of HCG or horse pituitary gonadotrophin twice daily for 3 days to 2 animals increased the progesterone secretion rate to 2.16 and 3.11 μg/ovary/min or to an average of 3.8 mg/ovary/24 hrs. There tends to be a significant relation between progesterone secretion rates and ovarian blood flow rates. Plasma progesterone concentrations do not necessarily reflect ovarian secretion rates because progesterone concentration is relatively dependent on blood flow rates. Progesterone was found in very small amount or not at all in vein blood from ovaries without corpus luteum tissue.