Increase In Intrauterine Pressure Research Articles

Collagen bundling and alignment in equibiaxially stretched human amnion

We study irreversible collagen arrangement processes in ex-vivo human amnions subjected to inflation tests, which simulate the mechanical conditions prior to and during the initiation of labor uterine contractions. The investigation is focused on the center of the membrane where the stresses are maximal and equibiaxial. Second harmonic generation reveals an unexpected collagen rearrangement in the compact layer that is responsible for the structural integrity of the fetal membrane. The observed bundling and alignment of the collagen fibers indicate a deviation from the expected equibiaxial stress state. The statistical analysis of the fiber orientations provides information on two driving forces for collagen alignment: microscale flaws and macroscale deviation from the equibiaxial strain. As the pressure increases, the macroscale effect becomes dominant, and a high density of fibers that are aligned along a specific direction is observed. A model that explains these observations and relates them to the material properties is presented. The results of this study indicate that a temporal increase in intrauterine pressure or uterine cervix dilatation causes irreversible changes in collagen molecular connections that may lead to biological changes, such as the initiation of term and preterm labor.

Uterine contractility changes in a perfused swine uterus model induced by local anesthetics procaine, lidocaine, and ropivacaine.

BackgroundLocal anesthetics (LAs) are increasingly used as therapeutics due to their multiple molecular effects. They may be potential agents also in gynecology and reproductive medicine. The objective of this study was to investigate the contractility response of the perfused swine uterus to different concentrations of the LAs procaine, lidocaine, and ropivacaine.Methods and findingsIn an extracorporeal perfusion model with fresh swine uteri, effects of administered boli of these three LAs in concentrations of 0.1 mg/mL, 0.5 mg/mL and 1.0 mg/mL on uterine contractility and peristalsis were assessed using an intrauterine double-chip micro-catheter. A dose-dependent increase in intrauterine pressure (IUP) in the isthmus and corpus uteri was observed after the administration of the ester-LA procaine 0.1, 0.5, and 1.0%, which was not seen with lower concentrations, or buffer solution. An increase-decrease curve was found after increasing concentrations of the amide-LA lidocaine and ropivacaine, with an IUP plateau with 0.1 and 0.5%, and a decrease with 1% (p<0.01). All reactions were seen in both the isthmus and corpus uteri. The difference of the contractility pattern between ester- and amide-LA at 1% concentration was significant.ConclusionLAs dose-dependently modulate contractility in non-pregnant swine uteri. The amid-LAs lidocaine and ropivacaine reduce contractility in higher concentrations and may be used as therapeutics in disorders with increased uterine contractility, as dysmenorrhoea, endometriosis, and infertility. The multiple molecular effects of LAs may explain these effects. This in-vitro pilot study in vitro provides initial data for designing further studies to transfer the results onto humans.

Outcome of Premature Rupture of Membranes – A Study of 120 Cases in Dhaka Medical College Hospital

Introduction: Premature rupture of membrane or PROM means when membrane ruptures before the onset of labour at a gestational age less than 37 completed weeks. In Bangladesh, every year, around 28,000 women die due to complications of pregnancy and childbirth. Nonscientific intervention in PROM made at various levels intensify the pregnancy complications several times, thereby leading many more deaths of foetus and newborn. Aetiology of PROM is largely unknown. The possible causes are either reduction of membrane strength or an increase in intrauterine pressure or both. Proper diagnostic facilities, proper monitoring and standard protocol in the management can improve the maternal and fetal outcome.Aim and objective: The aim of the study was to observe the incidence, type and maternal and fetal outcome of PROM.Materials and Method: A prospective case control analytical study was carried out at Dhaka Medical College Hospital, Dhaka from May ‘2000 to December‘2000. Total 120 patients were selected for this study among them 60 patients as case (Group A) and 60 patients were taken as control (Group B). Both primi and multigravida with Pregnancy more than 28 weeks with intact membrane as control and spontaneous rupture of membrane taken as case. High- risk patients such as hypertensive disorder of pregnancy, APH, cardiac disease, previous H/O caesarean section were excluded from the study. After taking proper history, speculum examination, some diagnostic investigations were carried out. Findings were recorded in predesigned questionnaire and statistical analysis were done using computerized software SPSS for Windows. A P value &lt; 0.05 was taken as significant.Results: In our study maternal complications were significantly higher in Group A patients (Chi-square test: X2 = 6.263, df= 1, P&lt; 0.05). Number of premature babies in PROM patients (25%) was significantly higher than control group. Perinatal morbidity was found higher in PROM (36.66%) compared to control group (31.66%). Most common morbidity was neonatal jaundice in PROM patients (13.33%) compared to babies of control group (8.33%).Conclusion: This study focused on certain risk factors in relation to PROM which can be preventable and reduce incidence and improvement of maternal and fetal outcome.J Dhaka Medical College, Vol. 25, No.2, October, 2016, Page 82-86

A Hypothesis for Self-Organization and Symmetry Reduction in the Synchronization of Organ-Level Contractions in the Human Uterus during Labor

We present a hypothesis for a mechanism involving self-organization of small functional units that leads to organ-level synchronization of uterine contractions in human labor. This view is in contrast to the long-held presumption that the synchronized behavior of the uterus is subject to well-defined internal organization (as is found in the heart) that exists prior to the onset of labor. The contractile units of the uterus are myocytes, which contract in response to both mechanical stretch and electrical stimulation. Throughout pregnancy progesterone maintains quiescence by suppression of “contraction-associated proteins” (CAPs). At the end of pregnancy a functional withdrawal of progesterone and an increasingly estrogenic environment leads to an increase in the production of CAPs. One CAP of particular importance is connexin 43, which creates gap junctions between the myocytes that cause them to become electrically coupled. The electrical connectivity between myocytes, combined with an increase in intrauterine pressure at the end of pregnancy shifts the uterus towards an increasingly unstable critical point, characterized by irregular, uncoordinated contractions. We propose that synchronous, coordinated contractions emerge from this critical point through a process of self-organization, and that the search for a uterine pacemaker has been unfruitful for the sole reason that it is non-existent.

Why the heart is like an orchestra and the uterus is like a soccer crowd

The human uterus has no pacemaker or motor innervation, yet develops rhythmic, powerful contractions that increase intrauterine pressure to dilate the cervix and force the fetus through the pelvis. To achieve the synchronous contractions required for labor, the muscle cells of the uterus act as independent oscillators that become increasingly coupled by gap junctions toward the end of pregnancy. The oscillations are facilitated by changes in resting membrane potential that occur as pregnancy progresses. Reductions of potassium channels in the myocyte membranes in late pregnancy prolong myocyte action potentials, further facilitating transmission of signals and recruitment of neighboring myocytes. Late in pregnancy prostaglandin production increases leading to increased myocyte excitability. Also late in pregnancy myocyte actin polymerizes allowing actin-myosin interactions that generate force, following myocyte depolarization, calcium entry, and activation of myosin kinase. Labor occurs as a consequence of the combination of increased myocyte to myocyte connectivity, increased depolarizations that last longer, and activated intracellular contractile machinery. During labor the synchronous contractions of muscle cells raise intrauterine pressure to dilate the cervix in a process distinct from peristalsis. The synchronous contractions occur in a progressively larger region of the uterine wall. As the size of the region increases with increasing connectivity, the contraction of that larger area leads to an increase in intrauterine pressure. The resulting increased wall tension causes myocyte depolarization in other parts of the uterus, generating widespread synchronous activity and increased force as more linked regions are recruited into the contraction. The emergent behavior of the uterus has parallels in the behavior of crowds at soccer matches that sing together without a conductor. This contrasts with the behavior of the heart where sequential contractions are regulated by a pacemaker in a similar way to the actions of a conductor and an orchestra.

Effect of carbetocin, oxytocin and prostaglandin E2 and F2α on intrauterine pressure in cows in dioestrus and oestrus.

To describe the physiological activity of the myometrium in oestrus and dioestrus and the induced activity after medication in cows with particular reference to segmental differences. Six cows were given the pharmaceuticals carbetocin, oxytocin and prostaglandin (PG) F2α (dinoprost) intramuscularly and PGE2 intravenously. The physiological myometrial activity was recorded for 15 minutes and the induced activity for 105 minutes by using a transcervically attached pressure probe containing six pressure microtransducers. Lower pressures were measured in dioestrus compared to oestrus before (dioestrus 3.2±8.88 mmHg, oestrus 12.4±13.23 mmHg, p<0.0001) and after the drug administration. Carbetocin provoked the longest lasting effect (60 minutes in dioestrus, 75 minutes in oestrus) followed by PGE2 (45 minutes in dioestrus, 60 minutes in oestrus), PGF2α (30 minutes each) and oxytocin (15 minutes in oestrus only). In contrast to the other drugs carbetocin did not cause any pressure decrease beneath the base level after the primary pressure increase in dioestrus. In dioestrus the pressure before drug administration was significantly higher in the cervix (3.6±19.40 mmHg) and the uterine body (7.1±36.10 mmHg) than in the uterine horn (1.1±7.21 mmHg). Conversely, in oestrus the pressure in the uterine horn (16.6±17.73 mmHg) was significantly higher than in the uterine body (6.2±16.59 mmHg) and the cervix (10.4±17.91 mmHg). Drug administration in dioestrus caused a cornual pressure increase and the pressure in the uterine body decreased, whereas in oestrus the pressure increased in all uterine segments. The physiological frequency of the pressure waves in dioestrus was 5.2±3.02 in 15 minutes compared to 7.5±2.89 in 15 minutes in oestrus. No traceable changes of the contraction frequency were found after medication. Carbetocin caused the most enduring increase in intrauterine pressure in dioestrus and oestrus and may therefore be indicated best for therapeutic use. The tested drugs had the same effects on the various uterine segments and no effect on the contraction frequency.

Effect of contextually congruent stallion vocalization playback on intrauterine pressure in the mare

Although oxytocin can be an effective treatment for persistent mating-induced endometritis (PMIE), frequent administration is required due to the short half-life of oxytocin and exogenous oxytocin may produce tetanic spasms of the myometrium. Teasing with a stallion during estrus elicits endogenous oxytocin secretion and uterine contractions, which may result in a more optimum physiologic response. Recently, it has been shown that mares will respond to contextually congruent stallion vocalization recordings with teasing behavior. The aim of this study was to determine if contextually congruent stallion vocalization would induce uterine contractions and increased uterine pressure in the mare. We hypothesized that teasing, contextually congruent stallion vocalization (with or without stallion scent), and exogenous oxytocin would increase intrauterine pressure in estrous pony mares, but that oxytocin would cause the greatest increases in intrauterine pressure. Changes in uterine pressure were recorded using a wireless telemetry capsule inserted into the uterine lumen (SmartPill pH.p Capsule), a novel method of instrumentation for uterine pressure studies. Twentyfour hours after administration of human chorionic gonadotropin, five reproductively normal pony mares were instrumented with an intrauterine telemetry pressure capsule during estrus. Baseline pressure was recorded for

Differences in muscarinic-receptor agonist–, oxytocin-, and prostaglandin-induced uterine contractions

To investigate the contractile response of the perfused swine uterus to various receptor pathways (oxytocin, prostaglandins, and muscarine). An extracorporeal perfusion model of the swine uterus was used that keeps the uterus in a functional condition and is appropriate for the study of physiologic questions. Oxytocin-, prostaglandin-, and carbachol-induced uterine contractility and peristalsis were assessed using an intrauterine double-chip microcatheter. University hospital. Intrauterine pressure profiles. A dose-dependent increase in intrauterine pressure (IUP) in the isthmus uteri and corpus uteri was observed after the administration of prostaglandin F(2alpha) (PGF(2alpha)) and oxytocin, which reached a plateau after further stimulation. A dose-dependent increase in IUP in the isthmus uteri and corpus uteri was also observed after the administration of prostaglandin E(1) (PGE(1)) and prostaglandin E(2) (PGE(2)), with a plateau in IUP in the middle-concentration range and a decrease during the further course of stimulation. After administration of PGE(1), PGE(2), and PGF(2alpha), different directions of contraction waves were also observed. Carbachol also showed a unique contractility pattern, with isolated, very powerful, dose-dependent contractions with an IUP gradient, suggesting directed transport from the upper region to the lower region. This study demonstrated that oxytocin, the prostaglandins, and carbachol modulate contractility in nonpregnant swine uteri in a characteristic way, resulting in different contractility patterns.

Uterine contractility in response to different prostaglandins: results from extracorporeally perfused non-pregnant swine uteri

Prostaglandins (PGs) are important stimulators of uterine contractility. Limited data are available at present on the effects of different PGs on uterine contractility, measured using intraluminal pressure changes in the complete uterus. The goal of this study was to assess dynamic changes in uterine contractility and peristalsis in response to PGs in comparison with the effects of oxytocin administration. An extracorporeal perfusion model of swine uteri was used, which keeps the uterus in a functional condition, and is appropriate for the study of physiological questions. Oxytocin- and PG-induced uterine contractility and peristalsis were assessed using an intrauterine double-chip microcatheter. A dose-dependent increase in intrauterine pressure (IUP) in the isthmus uteri (P < 0.001) and the corpus uteri (P < 0.001) was observed after the administration of PGF(2alpha) and oxytocin, which reached a plateau after further stimulation. A dose-dependent increase in IUP in the isthmus uteri (P < 0.001) and the corpus uteri (P < 0.001) was also observed after the administration of PGE(1) and PGE(2), with a plateau in IUP in the middle-concentration range and a decrease in the course of further stimulation. PGE(2) caused significantly more contractions starting in the corpus uteri and moving to the isthmus uteri (P = 0.008). The direction of most contractions caused by PGE(1), PGE(2) and oxytocin differed from that of PGF(2alpha). This study demonstrates that the PGs tested modulate contractility in non-pregnant swine uteri in a characteristic way, resulting in different contractility patterns.

Role of estrogen and progesterone in the regulation of uterine peristalsis: results from perfused non-pregnant swine uteri

Adequate uterine contractility and peristalsis are involved in the transport of semen and gametes and in successful embryo implantation. Estrogen and progesterone fluctuate characteristically during the menstrual cycle. It has been suggested that both hormones influence uterine peristalsis in characteristic ways. An extracorporeal perfusion model of the swine uterus was used that keeps the uterus in a functional condition and is suitable for the study of physiological questions. The effects of estrogen and progesterone on oxytocin-induced uterine peristalsis were assessed using an intrauterine double-chip microcatheter. Estrogen perfusion was associated with an increase in intrauterine pressure (IUP) in a dose-dependent manner. There was a significant difference between the IUP increase measured in the isthmus uteri and that in the corpus uteri, resulting in a cervico-fundal pressure gradient. Estrogen perfusion resulted in a significantly higher rate of peristaltic waves starting in the isthmus uteri and directed towards the corpus uteri. Progesterone was able to antagonize the estrogen effect in general. This study demonstrates that estrogen and progesterone have differential effects in the regulation of uterine peristalsis. The present observation shows that estrogen stimulates uterine peristalsis and is able to generate a cervico-fundal direction of peristalsis, whereas progesterone inhibits directed uterine peristalsis.

Perfused Non-Pregnant Swine Uteri: A Model for Evaluating Transport Mechanisms to the Side Bearing the Dominant Follicle in Humans

Adequate uterine contractility and periovulatory peristalsis, interpreted as "rapid sperm transport" to the side bearing the dominant follicle, may be a precondition for successful reproduction in humans. Estrogen and progesterone fluctuate characteristically during the menstrual cycle, and their source is the dominant follicle and corpus luteum. The question is, how is the direction to the left or right side of transport mechanisms influenced? An extracorporeal perfusion model of the swine uterus was used that maintained the uterus in a functional condition and that was suitable for the study of physiological questions. The effects of side-dependent estrogen, progesterone, and estrogen plus progesterone perfusion on oxytocin-induced uterine peristalsis were assessed using two intrauterine microcatheters placed in each horn of the swine uterus. Estrogen perfusion was associated with an increase in intrauterine pressure (IUP) in a dose-dependent manner only in the estrogen-perfused horn of the swine uterus. There was a significant difference between the IUP increase measured in the estrogen-perfused horn and that in the non estrogen-perfused horn of the swine uterus. Progesterone perfusion showed no effect in general. Furthermore, progesterone antagonized the estrogen effects. This study demonstrates that side-dependent estrogen perfusion resulted in side-dependent contractility in the swine uterus perfusion system used. These observations show that estrogen stimulates uterine contractility in the estrogen-perfused uterine horn and that estrogens may be the "trigger" for the transport mechanisms to the side bearing the dominant follicle during the periovulatory phase through their locally increased concentration and distribution via the utero-ovarian counter-current system in humans.

Increased uterine arterial pressure and contractility of perfused swine uterus after treatment with serum from pre-eclamptic women and endothelin-1

The present study was designed to examine the effects of ET-1 (endothelin-1) and serum from PE (pre-eclamptic), HP (healthy pregnant) and HNP (healthy non-pregnant) women on uterine arterial perfusion pressure and uterine contractility. Swine uteri (n = 25) were perfused for a period of up to 11 h, with the aim being to preserve a viable organ. Various concentrations of ET-1 as well as serum from PE, HP and HNP women (n = 10 per group) were administered to the perfused swine uteri and IUP (intrauterine pressure) and IAP (intra-arterial pressure) were recorded. ET-1 produced dose-dependent increases in IUP and IAP. The ET-1 concentration in serum was higher in serum from PE women than in HP and HNP women (P > 0.05). Administration of all serum samples had a contractile effect on the swine uterus, with the greatest effect being seen in HNP women (12.8 +/- 5.3 mmHg), followed by PE (9.06 +/- 4.2 mmHg) and HP (6.1 +/- 4.1 mmHg) women. Statistically significant differences were observed between HNP and PE women (P = 0.048), and PE and HP women (P = 0.021). Increases in IAP following administration of serum from PE women (48.8 +/- 20.0 mmHg) were significantly higher (P = 0.024) compared with the effect of serum from HP women (28.4 +/- 13.7 mmHg). In conclusion, the findings show that serum from PE women has significant vasoconstrictive and oxytocic effects compared with serum from HP women. In pre-eclampsia, the balance between vasorelaxing and vasoactive substances is disturbed.

Use of the alpha‐2 agonists xylazine and detomidine in the perianaesthetic period in the horse

Alpha-2 agonists have been widely used in equine anaesthesia since the clinical advent of xylazine in the 1970s (Clarke and Hall 1969; Kerr et al. 1972). Alpha-2 agonists produce sedation, muscle relaxation and analgesia by stimulation of α2 receptors centrally in the brain and spinal cord and peripherally (Hellyer et al. 2003). Two α2 agonists, xylazine and detomidine, are currently approved for use in the horse in the USA, while 2 additional drugs, romifidine and medetomidine, are approved for use in horses in other countries. Although differing in potency, α2 agonists share a common pharmacology. The degree of sedation, muscle relaxation and analgesia for a given drug is dose-dependent (England and Clarke 1996). Arterial blood pressure is initially increased due to drug-induced increases in peripheral vascular resistance (Wagner et al. 1991). The increases may be sustained (10–60 mins) when more potent α2 agonists like detomidine are used. Heart rate decreases, sinus arrhythmia and first and second degree atrioventricular blockade are common initial reflex mediated responses. Decreases in heart rate produce significant decreases in cardiac output, often to levels 50% of predrug values (Yamashita et al. 2000). Respiratory rate is usually decreased but this is offset by increases in tidal volume so that significant hypercarbia does not usually occur. Relaxation of the muscles of the upper airway occurs and can predispose the horse to respiratory stridor (Lavoie et al. 1992). Additional effects include sweating, ataxia, decreased salivation, decreased gastric secretions and gastrointestinal motility and increased urine volume. Swallowing is depressed; the passage of nasogastric tubes may therefore be more difficult and horses should be monitored for potential oesophageal obstruction. Other incidental effects of α2 agonist administration include increases in intrauterine pressure, hyperglycaemia and hypoinsulinaemia (von Reitzenstein et al. 2002). Alpha-2 agonists as analgesics

Effect of prostaglandin E 2, dl-cloprostenol, and prostaglandin E 2 in combination with d-cloprostenol on uterine motility during diestrus in experimental cows

Prostaglandin F 2α is used in dairy herd management because of its luteolytic properties and for its direct effect on the myometrium in cows diagnosed with endometritis. Prostaglandin E 2 has a contractile effect on the bovine uterus. In human medicine, prostaglandin E 2 is routinely used to maintain labor and to ripen the cervix. We hypothesized, that a combination of prostaglandin F 2α and prostaglandin E 2 would provoke a long-lasting increase in intrauterine pressure (IUP) and uterine motility as compared to either prostaglandin group. Intrauterine pressure was recorded during the diestrus of eight lactating dairy cows using a transcervically placed intraluminal pressure microtransducer. After recording of physiologic uterine motility for 30 min, prostaglandins ( dl-cloprostenol, PGE 2, PGE 2 in combination with d-cloprostenol) or placebo were administered, followed by a 2 h recording period. Significant differences were found for the area under the curve, the mean amplitude and the intrauterine pressure, whereas the number of pressure waves did not differ significantly among treatments. Peak values for area under the curve and mean amplitude were found during the first 15 min for the combination of PGE 2 and d-cloprostenol. During the last 15 min of the recording session, area under the curve and mean amplitude were increased only for the combination of PGE 2 and d-cloprostenol as compared to placebo. Although PGF 2α and PGE 2 provoke an increase in intrauterine pressure, only their combination guarantees a significant effect over a 2 h recording period.

Day of cycle affects changes in equine intrauterine pressure in response to teasing.

Oxytocin is released in response to teasing during both estrus and diestrus in mares, and at least during estrus, teasing results in an increase in electromyographic activity in the uterus. Exogenous oxytocin causes an increase in intrauterine pressure and prior studies have shown that this response is correlated to the day of the estrous cycle. To determine if teasing causes an increase in intrauterine pressure and if this response varies by day of the cycle, intrauterine pressure was measured while mares were teased with a stallion 2 days before ovulation, on the day ovulation was detected and 2 days after ovulation. A significant increase in intrauterine pressure was observed in response to teasing both 2 days before ovulation and on the day of ovulation, when plasma concentrations of progesterone were low. No significant increase in intrauterine pressure was observed in response to teasing 2 days after ovulation when progesterone concentrations were elevated. Management practices that include teasing or stallion exposure may be beneficial in stimulating uterine clearance mechanisms in mares during the preovulatory period.

Effect of different doses of prostaglandin E 2 on intrauterine pressure and uterine motility during diestrus in experimental cows

Studies in human medicine proved the important role of prostaglandin E 2, which stimulates uterine contractions in vivo and in vitro and has been extensively used to ripen the cervix around labor. We wanted to demonstrate that increasing the dosage of prostaglandin E 2 (1.25 mg, 2.5 mg, 5 mg and 10 mg) provokes an increase in intrauterine pressure and uterine motility in cattle. Five healthy, lactating dairy cows were used as experimental animals for this study. Intrauterine pressure was recorded during the diestrus phase (1 recording per cow and diestrus phase) by means of a transcervically placed intraluminal pressure microtransducer. Physiologic uterine motility was recorded for 30 min, then placebo or one of the prostaglandin E 2- dosages was administered through an indwelling catheter in the jugular vein, followed by a 2-h recording period (eight 15-min periods). Area under the curve (AUC), mean amplitude, frequency of pressure waves and intrauterine pressure were analyzed. Furthermore, we recorded protocols for monitoring heart and respiratory rates and side effects at 9 given examination times. Significant differences were found for the AUC, the mean amplitude and the intrauterine pressure (P ≤ 0.05), whereas the number of pressure waves per 15 min did not differ significantly among treatments. Peak values for AUC, mean amplitude and intrauterine pressure were found during the first 15 min after administration of 10 mg of prostaglandin E 2. Dose-effect curves showed that the 2.5 mg dosage provided the optimal ratio between myometrial stimulation and undesirable side-effects.

The effects of xylazine on intrauterine pressure, uterine blood flow, maternal and fetal cardiovascular and pulmonary function in pregnant goats.

To investigate the effects of xylazine on pregnant goats, xylazine induced changes in heart rate (HR), arterial blood pressure (ABP) and arterial blood pH and gases in the mother and fetus, as well as changes in intrauterine pressure (IUP) and uterine blood flow (UBF), were studied using a chronic preparation model of pregnant goats. Intramuscular administration of xylazine (0.2 mg/kg b.w.) caused a marked decrease in HR and ABP of the mother, which remained significantly reduced up to 120 min. In the fetus, a significant decrease in HR and a significant increase in ABP were recorded after only 5 min. Significant decreases of maternal arterial blood pH and oxygen partial pressure (Po2) were observed up to 120 and 30 min after the injection, respectively. Fetal arterial blood pH and Po2 also decreased, but these changes were milder and less persistent than those of the mother. Within 2 to 5 min after the administration of xylazine, IUP began to increase and remained high for about 15 min. Thereafter, there was a frequent periodic increase in IUP. After 5 min, UBF decreased significantly and remained low up to 120 min. A fall in UBF was associated with a rise in IUP. These findings suggested that administration of xylazine to pregnant goats results in a decrease in UBF arising from the induction of uterine contractions, a decrease in circulating blood volume, hypoxemia and acidosis in the mother.

Comparison of two dosages of prostaglandin F2a on canine uterine motility

The effect of 50 ug/kg prostaglandin F2a (PGF2a) was compared with 250 ug/kg PGF2a on uterine motility in the diestrous female. Microtipped pressure transducers were surgically implanted in the uteri of 6 females at 30 days diestrus and in 6 females at 60 days diestrus. Uterine responses to intravenous PGF2a (5 ug/kg), oxytocin (0.05 USP units/kg), and intramuscular PGF2a (50 ug/kg and 250 ug/kg) were measured in the awake females on Days 1 and 2 after implantation. There was no significant difference in the increase in intrauterine pressure produced by 50 ug/kg of PGF2a compared with 250 ug/kg of PGF2a. The longest duration of the effect occurred when 250 ug/kg of PGF2a were given. Side effects were also documented. Significantly more vomiting occurred when 250 ug/kg PGF2a were given than when 50 ug/kg PGF2a were administered. The only advantage to using a higher dosage of PGF2a appears to be the longer duration of motility.

Intracranial pressure and fetal heart rate in a hydrocephalic fetus during labor

Intra-uterine pressure (IUP), intracranial pressure (ICP) and fetal heart rate (FHR) were simultaneously recorded during labor in a severely hydrocephalic fetus. After cephalocentesis, 600 ml of liquor cerebrospinalis was drained. ICP exceeded IUP, but the increase in ICP was less than the increase in IUP during most of the contractions. The FHR showed marked decelerations during uterine contractions and changed gradually into a persistent bradycardia. The pathophysiology of fetal heart rate patterns during labor is discussed and the literature has been reviewed.

Uncoupling of excitation from contraction in uterine smooth muscle in near-term ewes

We infused forskolin in 30% ethanol or 30% ethanol systemically in seven chronically catheterized near-term sheep to determine the response of ovine uterine musculature to cyclic adenosine monophosphate stimulation. Maternal and fetal arterial pressure, fetal venous pressure, intrauterine pressure, and uterine electromyogram activity were monitored continuously. Prostaglandin E2 was infused at a delivery rate that caused a minimal 5 mm Hg increase in intrauterine pressure with definite contraction-like pressure spikes and associated uterine electromyogram activity. Forskolin (10 mg in 30% ethanol) or ethanol (vehicle) was then infused for 20 minutes. The prostaglandin E2 challenge was repeated 3 minutes later and again every 30 minutes over a 2 1/2-hour period. Data were analyzed by repeated measures analysis of variance. Infusion of ethanol (n = 2) had no apparent effect on either the intrauterine pressure or the uterine electromyogram response to prostaglandin E2 challenge. Forskolin infusion (n = 5) caused an attenuation of the intrauterine pressure response to prostaglandin E2 for 93 minutes. This effect was greatest 33 minutes after the infusion ended when the integrated pressure signal was 37% of the initial prostaglandin E2 response. The forskolin infusion had no effect on uterine electromyogram response to prostaglandin E2. We conclude that forskolin causes an uncoupling of excitation from contraction in the intact near-term ovine uterus.