The effects of thyroidectomy and thyroxine on the reactivity of rat uterine muscle to electrical stimulation in vitro
TL;DR: It is suggested that the thyroid hormone affects the intrinsic contractile state of the uterine smooth muscle.
About: This article is published in Pathophysiology.The article was published on 1994-07-01. It has received 3 citations till now. The article focuses on the topics: Thyroidectomy.
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TL;DR: Thyroxine treatment significantly potentiated the response of vasa deferentia to PGE2, when compared to controls, and it is suggested that thyroid hormones play a role in the contractile response of the vas deferens to P GE2.
Abstract: The effects of prostaglandin E2(PGE2) on the contractile activity of thyroidectomized and thyroxine treated albino rats were studied in vitro. Thyroidectomy totally inhibited the contractile response of the vas deferens to PGE2. Thyroxine treatment, on the other hand, significantly (P <. 001) potentiated the response of vasa deferentia to PGE2, when compared to controls. It is suggested that thyroid hormones play a role in the contractile response of the vas deferens to PGE2.
9 citations
TL;DR: The morphology and contractility of the vas deferens to electrical stimulation in vitro was investigated in thyroidectomized rats and rats treated with thyroxine, and Thyroxine treatment produced an overall hypertrophy of the layers.
2 citations
Cites background from "The effects of thyroidectomy and th..."
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...The intrinsic contractile state of the muscles of the diaphragm [9], heart [10], and uterus [3,11] have been reported to be profoundly influenced by the thyroid hormone activity....
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01 Jan 2013
TL;DR: There could perhaps be an insight into the cause of protracted labour and neonates with weak cry and low muscle tone and to that effect, possible interventions are recommended.
Abstract: Observations over the years, particularly in the labour rooms of Jos University Teaching Hospital (JUTH), and TANDAM Medical Centre, Jos, Plateau, Nigeria, indicates that several neonates respond differently to these parameters However, the experience of four mothers who had protracted labour and neonates with weak cry and low muscle tone, prompted this present investigation Ex-vivo placenta, maternal and cord blood of twenty deliveries (10 primipara and ten multipara; five of which were by elective caesarean section) were assayed for thyroid hormone in maternal serum and IgGp in maternal and cord sera; while the APGAR scores of the neonates were as well, documented Results showed that the mean immunoglobulin G population (IgGp) or density of neonates compared with that of their euthyriod mothers though higher in neonates was not statistically significant (P> 005) It was however significant (p < 001) between neonates and their hypothyroid mothers APGAR score of the neonates of the euthyroid mothers were higher (p < 005) than those hypothyroid mothers who also bled for longer periods postpartum It is our opinion that there could perhaps be an insight into the cause of such agonizing deliveries and to that effect, we recommended possible interventions Keywords : Euthyroidism, hypothyroidism, APGAR score, Gamma Immunoglobulin (IgG)
Cites background from "The effects of thyroidectomy and th..."
...Hypothyroidism has been reported earlier to cause feeble contraction (Tata, 1964); consequent on severe myotonia (Adeniyi et al., 1994; Amadi et al., 1999; 2007)....
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References
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TL;DR: The level of thyroid activity profoundly affects the intrinsic contractile state of cardiac muscle, independent of both norepinephrine stores and alterations in high energy phosphate stores, and, in addition, modifies the responsiveness of cardiac Muscle to inotropic agents.
Abstract: The intrinsic contractile properties of isolated cat papillary muscles and myocardial high energy phosphate stores were examined at three levels of thyroid activity and correlated with hemodynamic measurements in the intact animal. In addition, the relationship of thyroid state to endogenous norepinephrine stores and myocardial responsiveness to certain inotropic interventions were studied. In muscles from hyperthyroid cats, the velocity of shortening and the rate of tension development were markedly augmented, while duration of active state was decreased, compared to euthyroid muscles. These findings occurred in the presence and absence of intact norepinephrine stores and over a wide range of temperature and contraction frequency. The opposite changes occurred in muscles from hypothyroid cats. Isometric tension was slightly higher in muscles from hyperthyroid and lower in muscles from hypothyroid cats. The inotropic response to both norepinephrine and strophanthidin varied inversely with the level of thyroid state and allowed all three groups of muscles to reach a common ceiling of isometric tension regardless of thyroid state. Creatine phosphate and adenosine triphosphate stores were intact at all three levels of thyroid state. Thus, the level of thyroid activity profoundly affects the intrinsic contractile state of cardiac muscle, independent of both norepinephrine stores and alterations in high energy phosphate stores, and, in addition, modifies the responsiveness of cardiac muscle to inotropic agents.
387 citations
TL;DR: It is proposed that gap junctions are essential for normal labor and delivery for synchronous contraction of the muscle of the uterus and that agents used to stimulate or inhibit labor may do so by affecting gapjunctions.
Abstract: Gap junctions between smooth muscle cells of the myometrium of pregnant rats were found only immediately prior to, during and immediately after parturition by quantitative thin-section and freeze-fracture microscopy. Ovariectomy of 16- to 17-days-pregnant rats resulted in premature termination of pregnancy and the appearance of gap junctions. Methods that prolonged normal pregnancy in rats or maintained pregnancy in ovariectomized animals (progesterone treatment) prevented the appearance of gap junctions. Gap junctions formed in tissues incubated for 24--96 h in vitro without any hormonal influence. We propose that gap junctions are essential for normal labor and delivery for synchronous contraction of the muscle of the uterus. We present a model for control of parturition that may apply to other animals including humans. The model proposes: 1) the possible roles progesterone, prostaglandins, or estrogens may play in initiating gap-junction formation; 2) that the formation of gap junctions is a necessary step in activation of the myometrium leading to labor; and 3) that agents used to stimulate or inhibit labor may do so by affecting gap junctions.
177 citations
TL;DR: Thyroid hormones, gonadal and adrenocortical steroids, are glucoregulatory hormones, and glucocorticoids decrease glucose tolerance by increased hepatic glucose production and impaired peripheral glucose utilization.
Abstract: Thyroid hormones, gonadal and adrenocortical steroids, are glucoregulatory hormones. Thyroid hormones increase the provision of glucose to meet the enhanced energy demands which they impose. Glucose tolerance is decreased, associated with increased hepatic glucose production, although the glucose-raising effects of thyroid hormones are partially offset by an increased rate of glucose utilization especially in the postabsorptive state. The insulin secretory capacity of the pancreatic B cells is reduced by an excess of thyroid hormones, and the onset of diabetes may be hastened as pancreatic insulin reserves are depleted. Natural estrogens can improve glucose tolerance through a beta-cytotropic effect and enhanced insulin sensitivity. Progesterone may produce similar effects in the absence of estrogens, but progestins appear to antagonize the effects of estrogens. Testosterone exerts only marginal effects on glucose tolerance. Glucocorticoids decrease glucose tolerance by increased hepatic glucose production and impaired peripheral glucose utilization. Glucocorticoids reduce insulin sensitivity and responsiveness in peripheral tissues. However, the diabetogenic influence of glucocorticoid excess is partly compensated by a beta-cytotropic effect and a condition of diabetes develops when the functional reserve of the endocrine pancreas becomes limiting.
150 citations
TL;DR: It is suggested that females may have decreased calcitonin reserve and the stimulatory effect of pentagastrin was greater in males than in females.
Abstract: A sensitive RIA for human calcitonin has been developed which can detect 1-2 pg hormone. This procedure permits the measurement of the low concentrations of calcitonin in the unextracted plasma of normal human subjects. In 55 normal adults, mean plasma calcitonin was 24 pg/ml with an SD of ±18 pg/ml, an SE of ±2 pg/ml, and a range of < 10–75 pg/ml. There were no discernible age or sex differences in basal hormone concentration. Infusions of calcium, pentagastrin, and glucagon stimulated plasma calcitonin, whereas food and oral calcium did not. The stimulatory effect of pentagastrin was greater in males than in females. These data demonstrate that the low concentration of calcitonin in humans can be stimulated by several secretagogues and suggest that females may have decreased calcitonin reserve.
121 citations
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01 Jan 1984
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Abstract: Want to get experience? Want to get any ideas to create new things in your life? Read smooth muscle contraction now! By reading this book as soon as possible, you can renew the situation to get the inspirations. Yeah, this way will lead you to always think more and more. In this case, this book will be always right for you. When you can observe more about the book, you will know why you need this.
80 citations