Related Experiment Videos
The smooth muscle cell. I. In vivo synthesis of connective tissue proteins
Insights
Rat aortic smooth muscle cells synthesize and secrete connective tissue proteins like collagen and elastic fibers. Estrogen stimulation enhances this protein synthesis and secretion in myometrial cells.
Area of Science:
- Biochemistry
- Cell Biology
- Developmental Biology
Background:
- Smooth muscle cells play a crucial role in tissue development and maintenance.
- Understanding amino acid utilization in protein synthesis is key to tissue engineering and regenerative medicine.
Purpose of the Study:
- To investigate the capacity of prepubertal rat aortic smooth muscle cells to synthesize and secrete connective tissue proteins.
- To examine the influence of estradiol-17-beta on protein synthesis and secretion in aortic and myometrial cells.
Main Methods:
- Intravenous injection of proline-(3)H into prepubertal rats pre-treated with alcohol carrier or estradiol-17-beta.
- Analysis of aortic smooth muscle and myometrial cells using light and electron microscope radioautography at 15 min, 30 min, and 4 hr post-injection.
Main Results:
- Aortic smooth muscle cells in both groups rapidly took up and secreted proline into collagen and elastic fibers within 4 hours.
- Estrogen-stimulated myometrial cells also showed rapid proline uptake and secretion.
- Non-stimulated myometrial cells exhibited limited proline uptake and retention.
Conclusions:
- Developing aortic smooth muscle cells possess the ability to synthesize and secrete extracellular matrix proteins.
- Estrogen stimulation significantly enhances protein synthesis and secretion in myometrial cells, highlighting hormonal influence on connective tissue remodeling.
Abstract:
These studies have examined the ability of smooth muscle cells from developing aorta of the prepubertal rat to utilize amino acids in the synthesis and secretion of connective tissue proteins. Prepubertal rats, previously given either an alcohol carrier or estradiol-17-beta, were each given an intravenous injection of proline-(3)H. The animals were sacrificed after 15 and 30 min, and 4 hr. Light and electron microscope radioautographs of the aortic smooth muscle and of the myometrial cells demonstrated that the aortic cells, in both groups of animals, and the myometrial cells, in the estrogen-stimulated animals, took up the proline and rapidly secreted it in both collagen and elastic fibers within 4 hr. In contrast, the myometrial cells of the nonstimulated animal took up relatively small amounts of proline and retained most of the amino acid within the cells. Electron microscope radioautographs demonstrated that the organelles involved in this activity were the rough endoplasmic reticulum and Golgi complex together with peripheral elements, presumed to be small vesicles. These studies have demonstrated that the smooth muscle cells of the developing aorta and of the estrogen-stimulated myometrium have a capacity to synthesize and secrete proteins associated with the extracellular connective tissue matrix.