Regional differences in myosin heavy chain isoform expression and maximal shortening velocity of the rat vaginal wall smooth muscle

Basha, Maureen; Chang, Shaohua; Smolock, Elaine M.; Moreland, Robert S.; Wein, Alan J.; Chacko, Samuel

doi:10.1152/ajpregu.00118.2006

Cited by 10 publications

(29 citation statements)

References 49 publications

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“…Ovariectomy had no effect on myosin ATPase activity as estimated by V max of the proximal vaginal strips. Values obtained using tissue strips from ovariectomized animals were similar (0.10 ± 0.01 muscle lengths/second) to our previous report of V max of proximal vagina strips from control rats (0.11 ± 0.04 muscle lengths/second) using identical procedures .…”

Section: Resultssupporting

confidence: 87%

“…For histological procedures, the vagina was placed in Histochoice fixative (Amresco, Solon, OH, USA) and paraffin embedded. For physiological and molecular studies, the vagina was cut open longitudinally and the proximal vagina (upper 2/3) was dissected from the distal vagina as outlined by Basha et al [18]. Proximal vaginal segments were either snap frozen in liquid nitrogen and stored at -80°C or placed in ice-cold 3-(Nmorpholino)propanesulfonic (MOPS)-buffered physiological salt solution (PSS) for same-day physiological studies.…”

Section: Vaginal Tissue Preparationmentioning

confidence: 99%

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Effect of Estrogen on Molecular and Functional Characteristics of the Rodent Vaginal Muscularis

Basha

Chang

Burrows

et al. 2013

The Journal of Sexual Medicine

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Introduction Vaginal atrophy is a consequence of menopause however little is known concerning the effect of a decrease in systemic estrogen on vaginal smooth muscle structure and function. As the incidence of pelvic floor disorders increases with age, it is important to determine if estrogen regulates the molecular composition and contractility of the vaginal muscularis. Aim The goal of this study was to determine the effect of estrogen on molecular and functional characteristics of the vaginal muscularis utilizing a rodent model of surgical menopause. Methods 3–4 month old Sprague Dawley rats underwent sham laparotomy (Sham, n=18) or ovariectomy (Ovx, n=39). Two weeks following surgery, animals received a subcutaneous osmotic pump containing vehicle (Sham, Ovx) or 17- β estradiol (Ovx). Animals were euthanized one week later and the proximal vagina was collected for analysis of contractile protein expression and in vitro studies of contractility. Measurements were analyzed using a one-way ANOVA followed by Tukey's post hoc analysis (α= 0.05). Main Outcome Measures Protein and mRNA transcript expression levels of contractile proteins, in vitro measurements of vaginal contractility Results Ovariectomy decreased the expression of carboxyl-terminal myosin heavy chain isoform SM1 and h-caldesmon and reduced the amplitude of contraction of the vaginal muscularis in response to KCl. Estradiol replacement reversed these changes. No differences were detected in the % vaginal muscularis, mRNA transcript expression of amino terminal MHC isoforms, l-caldesmon expression and maximal velocity of shortening. Conclusion Systemic estrogen replacement restores functional and molecular characteristics of the vaginal muscularis of ovariectomized rats. Our results indicate that menopause is associated with changes in the vaginal muscularis, which may contribute to the increased incidence of pelvic floor disorders with age.

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Section: Resultssupporting

confidence: 87%

Section: Vaginal Tissue Preparationmentioning

confidence: 99%

Effect of Estrogen on Molecular and Functional Characteristics of the Rodent Vaginal Muscularis

Basha

Chang

Burrows

et al. 2013

The Journal of Sexual Medicine

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“…The majority of in vitro studies of vaginal smooth muscle have investigated signaling pathways responsible for inducing relaxation of the distal vagina (3,14,15,19,20,40). In support of the suggestion that regional differences are present in vaginal smooth muscle responses to PNS, we have provided molecular and functional evidence that the rat proximal vagina is composed of a phasictype smooth muscle compared with a tonic-type smooth muscle in the distal vagina (5). Together, these studies emphasize the importance of accounting for regional differences in structure and function when studying the vaginal muscularis.…”

supporting

confidence: 54%

“…The vaginal tube was isolated, dissected from the urogenital tract, cleaned of connective tissue, and cut open longitudinally. The vagina was divided into a proximal (approximately upper two-thirds) and distal segment (approximately lower one-third) under a dissecting microscope as described by Basha et al (5). The vaginal segments were either snap frozen in liquid nitrogen and stored at Ϫ80°C or placed in ice-cold MOPS-buffered physiological salt solution (PSS) for same-day physiological studies.…”

Section: Animal Studiesmentioning

confidence: 99%

Functional significance of muscarinic receptor expression within the proximal and distal rat vagina

Basha

LaBelle

Northington

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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Information regarding the role of cholinergic nerves in mediating vaginal smooth muscle contraction is sparse, and in vitro studies of the effects of muscarinic agonists on vaginal smooth muscle are discrepant. The goal of this study was to determine the expression of muscarinic receptors in the vaginal wall of the rat. In addition, we sought to determine the effect of the muscarinic receptor agonist carbachol on contractility and inositol phosphate production of the proximal and distal rat vaginal muscularis. RT-PCR analysis indicated that both M(2) and M(3) receptor transcripts were expressed within the proximal and distal rat vagina. Carbachol dose-dependently (10(-7)-10(-4) M) contracted the rat vaginal muscularis with a greater maximal contractile response in the proximal vagina (P < 0.01) compared with the distal vagina. The contractile responses of the rat vaginal muscularis to carbachol were dose dependently inhibited by the M(3) antagonist para-fluoro-hexahydrosiladefenidol, and a pK(B) of 7.78 and 7.95 was calculated for the proximal and distal vagina, respectively. Inositol phosphate production was significantly increased in both regions of the vagina following 20-min exposure to 50 muM carbachol with higher levels detected in the proximal vagina compared with the distal (P < 0.05). Preliminary experiments indicated the presence of M(2) and M(3) receptors in the human vaginal muscularis as well as contraction of human vaginal muscularis to carbachol, indicating that our animal studies are relevant to human tissue. Our results provide strong evidence for the functional significance of M(3) receptor expression in the vaginal muscularis.

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“…Basal tone, however, is negatively associated with POP, indicating its importance [16]. Similarly, maximum tone of the vaginal wall is primarily investigated [13,14,[17][18][19][20][21], but the VaSM basal contribution may also be of significance [22][23][24]. Along the circumferential axis, maximum tone is greater in the proximal than the distal region of the vaginal wall [18].…”

Section: Introductionmentioning

confidence: 99%

Smooth muscle regional contribution to vaginal wall function

et al. 2019

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Pelvic organ prolapse is characterized as the descent of the pelvic organs into the vaginal canal. In the USA, there is a 12% lifetime risk for requiring surgical intervention. Although vaginal childbirth is a well-established risk factor for prolapse, the underlying mechanisms are not fully understood. Decreased smooth muscle organization, composition and maximum muscle tone are characteristics of prolapsed vaginal tissue. Maximum muscle tone of the vaginal wall was previously investigated in the circumferential or axial direction under uniaxial loading; however, the vaginal wall is subjected to multiaxial loads. Further, the contribution of vaginal smooth muscle basal (resting) tone to mechanical function remains undetermined. The objectives of this study were to determine the contribution of smooth muscle basal and maximum tone to the regional biaxial mechanical behaviour of the murine vagina. Vaginal tissue from C57BL/6 mice was subjected to extension–inflation protocols ( n = 10) with and without basal smooth muscle tone. Maximum tone was induced with KCl under various circumferential ( n = 5) and axial ( n = 5) loading conditions. The microstructure was visualized with multiphoton microscopy ( n = 1), multiaxial histology ( n = 4) and multiaxial immunohistochemistry ( n = 4). Smooth muscle basal tone decreased material stiffness and increased anisotropy. In addition, maximum vaginal tone was decreased with increasing intraluminal pressures. This study demonstrated that vaginal muscle tone contributed to the biaxial mechanical response of murine vaginal tissue. This may be important in further elucidating the underlying mechanisms of prolapse, in order to improve current preventative and treatment strategies.

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Regional differences in myosin heavy chain isoform expression and maximal shortening velocity of the rat vaginal wall smooth muscle

Cited by 10 publications

References 49 publications

Effect of Estrogen on Molecular and Functional Characteristics of the Rodent Vaginal Muscularis

Effect of Estrogen on Molecular and Functional Characteristics of the Rodent Vaginal Muscularis

Functional significance of muscarinic receptor expression within the proximal and distal rat vagina

Smooth muscle regional contribution to vaginal wall function

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