Biological Actions of Relaxin in Pigs and Beef Cattle*

Anderson, Lloyd L.; Pérezgrovas, R.; O'Byren, E. M.; Steinetz, Bernard G.

doi:10.1111/j.1749-6632.1982.tb18036.x

Cited by 28 publications

(14 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…40 -42,45-47 The concentrations of RLX found by us to be effective in stimulating the response of BASMCs are higher than those measured in bovine plasma. 67 Nevertheless, the possibility that RLX actually plays a role in the regulation of vascular smooth muscle tone and organ blood perfusion under physiological conditions should not be ruled out. In fact, it should be borne in mind that (1) measurements of plasma levels of RLX performed in the past by radioimmunoassay with heterologous antibodies may have underestimated the actual physiological levels of this hormone and (2) SMCs, after explantation from the arterial wall and adaptation to in vitro culture conditions, may reduce their responsiveness to vasoactive agents, possibly owing to partial dedifferentiation or reduction of receptors.…”

Section: Discussionmentioning

confidence: 99%

Relaxin Activates the l -Arginine–Nitric Oxide Pathway in Vascular Smooth Muscle Cells in Culture

Bani

Failli²,

Bello³

et al. 1998

Hypertension

138

134

View full text Add to dashboard Cite

Abstract-The peptide hormone relaxin (RLX) has been shown to elicit a powerful vasodilatory response in several target organs. This response is mediated by the stimulation of intrinsic nitric oxide (NO) generation. The present study was designed to clarify whether RLX directly promotes the relaxation of vascular smooth muscle cells through stimulation of NO generation. Vascular smooth muscle cells from bovine aortas were incubated with RLX at concentrations ranging from 1 nmol/L to 1 mol/L. The expression and activity of NO synthase, production of NO, and the intracellular levels of cGMP and Ca 2ϩ were determined. The cell morphology and signal transduction mechanisms of these bovine aortic smooth muscle cells in response to RLX were also studied. RLX stimulated the expression of immunoreactive inducible NO synthase and increased significantly and in a concentration-related fashion inducible NO synthase activity, NO generation, and intracellular cGMP levels. Concurrently, RLX significantly decreased cytosolic Ca 2ϩ concentrations and caused changes in cell shape and the actin cytoskeleton that were consistent with cell relaxation. The signal transduction mechanisms leading to the enhanced expression of inducible NO synthase protein and activity caused by RLX involve the activation of tyrosine kinase, phosphatidylcholine-phospholipase C, and the transcription factor nuclear factor-B, similar to bacterial endotoxins and proinflammatory cytokines. This study suggests that RLX is an endogenous agent capable of regulating vascular tone by activation of the L-arginine-NO pathway in vascular smooth muscle cells. Key Words: muscle, smooth, vascular Ⅲ relaxin Ⅲ nitric oxide R elaxin is a peptide hormone of Ϸ6 kDa that is predominantly produced by the ovaries and is best known for its actions on the female reproductive system.1 Recently, evidence has been accumulating that RLX has additional multiple effects on organs other than the reproductive ones. In particular, previous research in our laboratory has shown that RLX exerts a powerful effect on blood vessels, causing vasodilation in the uterus, mammary gland, pigeon crop sac, mesocecum, and coronary system. 2-8 Our findings fit well with those of other authors that RLX also decreases blood pressure in spontaneously hypertensive rats.9,10 All of the above findings support the idea that RLX is effective in reducing vascular tone. Concerning the mechanism of action of RLX on its target organs, our studies of coronary vessels in the isolated, perfused rat and guinea pig heart 7,8 have shown that the vasodilatory action of RLX is mediated by stimulation of endogenous production of NO, which is a powerful vasorelaxant. 11,12 It is worth noting that stimulation of intrinsic NO production is also involved in the response to RLX in different cells, such as rat and guinea pig serosal mast cells, 13 human and rabbit platelets, 14 and mammary adenocarcinoma MCF-7 cells. 15There is general agreement that the vasodilatory action of NO is primarily an endothelium-dependent process. I...

show abstract

Section: Discussionmentioning

confidence: 99%

Relaxin Activates the l -Arginine–Nitric Oxide Pathway in Vascular Smooth Muscle Cells in Culture

Bani

Failli²,

Bello³

et al. 1998

Hypertension

138

134

View full text Add to dashboard Cite

show abstract

“…The porcine relaxin RIA has been used to measure relaxin secretion in pregnancy and during parturition in beef cattle (30). Relaxin levels were low (<200 pg/ml) in late pregnancy right up to the time of parturition, when a significant rise of relaxin to approximately 800 pg/ml occurred at parturition only, with an abrupt decline to very low levels postpartum.…”

Section: The Application Of the Homologous Porcine Riamentioning

confidence: 99%

Relaxin as a New Hormone*

Bryant‐Greenwood

1982

Endocrine Reviews

137

View full text Add to dashboard Cite

“…During late pregnancy, bovine corpora lutea produce biologically active relaxin; however, the concentrations are markedly lower than those in pigs on the basis of inhibition of uterine contractility and homologous RIA for porcine relaxin (14)(15)(16). Pelvic area increases gradually in cattle throughout gestation, then the rate increases during the last 4 days preceding normal parturition, which coincides with increasing blood concentrations of 17/3-estradiol (17jS-E 2 ) and estrone (Ei) (15)(16)(17)(18)(19)(20). Administration of porcine relaxin increases both pelvic area and cervical dilatation in beef heifers during late pregnancy (21,22).…”

mentioning

confidence: 98%

“…It also is produced by the human corpus luteum during the menstrual cycle as well as by the basal plate cells of the placenta and decidual cells (10)(11)(12)(13). During late pregnancy, bovine corpora lutea produce biologically active relaxin; however, the concentrations are markedly lower than those in pigs on the basis of inhibition of uterine contractility and homologous RIA for porcine relaxin (14)(15)(16). Pelvic area increases gradually in cattle throughout gestation, then the rate increases during the last 4 days preceding normal parturition, which coincides with increasing blood concentrations of 17/3-estradiol (17jS-E 2 ) and estrone (Ei) (15)(16)(17)(18)(19)(20).…”

mentioning

confidence: 98%

Relaxin on Induction of Parturition in Beef Heifers*

et al. 1986

Self Cite

View full text Add to dashboard Cite

Purified porcine relaxin (3000 U/mg) was administered into the cervical os of primiparous beef heifers on day 278 of gestation (approximately 5 days before parturition normally occurs) to determine its effects on the induction of parturition, changes in progesterone, estrone (E1), 17 beta-estradiol (17 beta-E2), cervical dilation, and pelvic relaxation. Heifers were assigned randomly to 1 of 3 treatments: relaxin-double (two infusions of 3000 U, 12 h apart; n = 17), relaxin-single (3000 U; n = 14), and PBS-gel vehicle (n = 16). Relaxin induced marked earlier calving (P less than 0.002) than PBS-gel vehicle. The intervals between the administration of relaxin or the PBS-gel vehicle and calving were 2.0, 2.5, and 5.3 days for heifers given relaxin-double, relaxin-single, and PBS-gel vehicle, respectively. The duration of gestation was significantly reduced (P less than 0.002) in relaxin-treated heifers compared with that in control heifers. A precipitous decrease in progesterone (7.1 ng/ml) occurred in peripheral blood plasma within 24 h after relaxin treatment. Coincident with a decline in levels of progesterone, E1 and 17 beta-E2 increased by 1700 and 400 pg/ml, respectively, an increase of 35% compared with the 12% increase in these steroids in control heifers. Mean deviations of cervical dilation increased 643%, 526%, and 11% in heifers given relaxin-double, relaxin-single, and PBS-gel vehicle, respectively. Relaxin induced maximum pelvic opening between 12-36 h after treatment. Although relaxin induced significantly earlier calving, there was no incidence (0 of 31 heifers) of retained placenta. We conclude from this study that purified relaxin administered intracervically to primiparous beef heifers during late pregnancy induced premature parturition. Marked shifts of progesterone, E1, 17 beta-E2, pelvic canal expansion, and cervical relaxation reflect the premature parturition induced by relaxin.

show abstract

Biological Actions of Relaxin in Pigs and Beef Cattle*

Cited by 28 publications

References 31 publications

Relaxin Activates the l -Arginine–Nitric Oxide Pathway in Vascular Smooth Muscle Cells in Culture

Relaxin Activates the l -Arginine–Nitric Oxide Pathway in Vascular Smooth Muscle Cells in Culture

Relaxin as a New Hormone*

Relaxin on Induction of Parturition in Beef Heifers*

Contact Info

Product

Resources

About