Vasodilator effect of parathyroid hormone-related protein in the perfused rat tail artery

Paspaliaris, Vasilis; Leaver, D. D.; Tj, Martin; Rand, M. J.

doi:10.1016/0169-6009(90)90325-a

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“…1989;Paspaliaris & Leaver, 1990) and non-vascular (Shew et al 1984(Shew et al , 1991Mok, Eberechukwu, Martin et al 1989) smooth muscle. In this study, we found that PTHrP(l 34) relaxed spon¬ taneous and electrically evoked contractions of rat isolated non-gravid uterine horns at a concentration as low as 10 pmol/1.…”

Section: Discussionmentioning

confidence: 97%

“…In this study, we found that PTHrP(l 34) relaxed spon¬ taneous and electrically evoked contractions of rat isolated non-gravid uterine horns at a concentration as low as 10 pmol/1. Thus, uterine muscle is appreci¬ ably more sensitive to PTHrP(l-34) than either vas¬ cular or gastric smooth muscle (Pang et al 1985;Mok et al 1989;Nickols et al 1989;Paspaliaris & Leaver, 1990). Of particular note in the present experiments is that the sensitivity of uterine horns to PTHrP and the amplitude of relaxation induced by PTHrP in noncycling rats were significantly increased by oestrogen treatment for 1 day (approximately 1000-fold) and further increased (approximately tenfold) by 2 days of oestrogen treatment, when compared with untreated rats.…”

Section: Discussionmentioning

confidence: 98%

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Oestrogen enhancement of the myometrial response to exogenous parathyroid hormone-related protein (PTHrP), and tissue localization of endogenous PTHrP and its mRNA in the virgin rat uterus

Paspaliaris

Vargas

Gillespie

et al. 1992

Journal of Endocrinology

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Classical pharmacological studies have shown that oestrogen dominance in humans and other animals can increase the responsiveness of the uterus to many locally acting peptides. Parathyroid hormone-related protein (PTHrP) has been shown to be expressed in the pregnant and non-pregnant rat uterus and exogenous PTHrP is known to relax uterine contraction in vitro. We investigated whether oestrogen dominance can influence the responsiveness of the uterine horn to PTHrP, and further studied the localization of PTHrP mRNA and protein in the rat uterine horn using in-situ hybridization and immunohistochemistry. Exogenous PTHrP(1-34) inhibited spontaneous and electrically induced contractions in uteri isolated from non-cycling rats. Pretreatment of non-cycling rats with oestradiol-17 beta increased uterine sensitivity to PTHrP: EC50 values for inhibition of spontaneous contractions by PTHrP were 0.33 nmol/l, 1.1 nmol/l, 2.6 nmol/l and 7800 nmol/l in uteri from animals treated for 2 days with oestradiol-17 beta alone, 2 days with oestradiol-17 beta + 1 day progesterone, 1 day with oestradiol-17 beta alone and in untreated rats respectively. Similar EC50 values were obtained for electrically stimulated uteri. In agreement with these findings, uterine horns from cycling rats in pro-oestrous and oestrous phases of the cycle showed a higher responsiveness to PTHrP(1-34) when compared with uterine horns taken from rats in metoestrus and dioestrus. PTHrP mRNA and protein were detected in the endometrial epithelium lining of the lumen and the endometrial glands, as well as in the myometrium of rats which were either pretreated for 2 days with oestradiol-17 beta or untreated. This study suggests that PTHrP may act in an autocrine and/or paracrine manner to modulate uterine motility and function.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 98%