Relaxation-induced contraction of smooth muscle surrounding hamster ovarian follicles
Changes in intrafollicular pressure and follicular diameter resulting from injecting or withdrawing fluid from the antrum were measured in preovulatory follicles and used as an assay for changes in tension in the follicular wall by applying the Laplace relationship for thin-walled spheres. Passive l...
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Published in | Journal of reproduction & fertility Vol. 85; no. 2; pp. 593 - 603 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
England
Society for Reproduction and Fertility
01.03.1989
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Subjects | |
Online Access | Get full text |
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Summary: | Changes in intrafollicular pressure and follicular diameter resulting from injecting or withdrawing fluid from the antrum
were measured in preovulatory follicles and used as an assay for changes in tension in the follicular wall by applying the
Laplace relationship for thin-walled spheres. Passive length–tension curves were constructed from pressure–volume measurements
to establish baseline wall stiffness. Any subsequent change in pressure could then be compared to the length–tension curves
to evaluate whether it arose from active tension development or from passive stretch. When intact follicles (1–2 h before
ovulation) were subjected to release of passive stretch, they exhibited a contractile response that lasted 15 sec–2 min and
was characterized by cyclic increases and decreases in tension, with a period of 1 cycle every 2–3 sec. The probability of
activating a response in the tissue was most strongly correlated with the rate of release of passive stretch. Intrafollicular
pressures generated during active contractile responses sometimes reached 80 mmHg (10·64 mPa), corresponding to a wall tension
of 5332 dynes/cm (5·332 N/m) (for a 1 mm follicle) and were clearly well above the passive length–tension curves. Passive
stretching of the follicular wall during a contractile response to 5-hydroxytryptamine stimulation resulted in large reductions
in active wall tension for the duration of the stretch. These results are consistent with a stretch-activated inhibition of
contractile events.
Keywords: ovulation; Laplace formula; follicle; smooth muscle |
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ISSN: | 0022-4251 1470-1626 1741-7899 |
DOI: | 10.1530/jrf.0.0850593 |