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.
Department of Physiology and Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia. m.matuszek@unsw.edu.au
Maria A
MA
Matuszek
Karen J
KJ
Gibson
Eugenie R
ER
Lumbers
Giuseppe
G
Simonetta
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