Impact of cortisol on alpha-actin content in vascular smooth muscle cells of fetal sheep.
The effects of gestation on a-actin levels in vascular smooth muscle aortae were studied in 31 fetal sheep, aged 66-144 days (term=150 days). Aortae were collected post-mortem. 2. Aortae, carotid and femoral arteries from two groups of chronically catheterized fetal sheep (110-114 days) were also examined. One group was infused with cortisol (n=6; hydrocortisone sodium succinate, total dose 16.8 mg in 48 h) and the control group received saline (0.15 mol/L, 0.33 mL/h, n=7). 3. Vascular homogenate protein was separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and western transfer. a-Actin was identified using a monoclonal mouse anti-a actin antibody and standardized against tissue protein and DNA content. 4. Between 60 and 144 days gestation, there was an exponential increase in the a-actin content of vascular smooth muscle cells from fetal sheep aorta (P<0.0001). a-Actin concentration (densitometry units (U) relative to DNA 260 nm absorbance (Abs)) was significantly (P<0.05) higher in the aortae of cortisol-infused (12,601+/- 2,499 U/Abs) fetal sheep compared with those that were saline-infused (4,514+/-670 U/Abs). a-Actin (relative to DNA absorbance) of carotid and femoral vessels in cortisol-infused animals (20,659+/- 4,812 U/Abs) compared with those that were saline-infused (14,461+/- 2,645 U/Abs) was increased, but the difference was not significant. 5. Therefore, the a-actin concentration of the vascular smooth muscle of the aorta increases throughout gestation. Cortisol treatment is associated with further increases in a-actin concentration in the fetal aorta, indicating that the development of large conduit vessels can be altered by this glucocorticoid.
Matuszek
Maria A
MA
Department of Physiology and Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia. m.matuszek@unsw.edu.au
Gibson
Karen J
KJ
Lumbers
Eugenie R
ER
Simonetta
Giuseppe
G
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D015153:Blotting, Western; D004247:DNA / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005865:Gestational Age; D006854:Hydrocortisone / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000196:embryology / Q000201:enzymology*; D011247:Pregnancy; D011506:Proteins / Q000378:metabolism; D012756:Sheep
D000199:Actins; D011506:Proteins; D004247:DNA; D006854:Hydrocortisone