21. One of the key experiments to show that gap junctions allow the passage of s

Question

21. One of the key experiments to show that gap junctions allow the passage of small molecules
from one cell to another was carried out by allowing cardiac muscle cells to interact with ovarian
granulosa cells. Cardiac muscle cells respond to norepinephrine by contraction whereas ovarian
granulosa cells respond to FSH (follicular stimulating hormone) by undergoing various metabolic
changes. The researchers that performed this experiment added FSH to the mixed cell culture and
observed the contraction of the muscle cells. Explain how the muscle cells could respond to FSH.

Explanation / Answer

Hi!!!!!!! Hope this answer will help you to understand the concept :) Human myometrial smooth muscle cells contain receptors for human chorionic gonadotropin (hCG)/luteinizing hormone (LH). Exogenous hCG and LH can cause a modest hyperplasia in myometrial smooth muscle cells in culture. This response is lost after about the third subculture of the cells. The present study investigated whether the loss of hCG response could be restored by co-culturing with human follicle stimulating hormone (FSH). The results showed that co-culturing with FSH can indeed restore a modest mitogenic response of hCG. However, FSH alone was not mitogenic. The FSH restoration of hCG response can be blocked by antibodies to FSH or hCG but not by non-specific rabbit IgG. The FSH treatment resulted in an increase of steady state levels of hCG/LH receptor mRNA and protein in myometrial smooth muscle cells. Since the FSH actions could be receptor mediated, we investigated the presence of FSH receptor mRNA transcripts and protein in freshly dispersed myometrial smooth muscle cells. Northern blotting demonstrated that myometrial smooth muscle cells, just as rat ovary, a classical target of FSH action, contain multiple FSH receptor mRNA transcripts.

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