Interleukin-1 beta alters actin expression and inhibits contraction of rat thoracic aorta.
Previous studies have indicated that interleukin-1 beta (IL-1) inhibits contraction of rat aortas by activating nitric oxide production in vascular smooth muscle cells, with subsequent increases in guanosine 3',5'-cyclic monophosphate (cGMP). This study determined if the effect of IL-1 involves the primary regulatory event in smooth muscle activation, myosin light chain (MLC) phosphorylation. This study also examined whether IL-1 affects contractile protein content. IL-1 (20 ng/ml) significantly decreased stress in response to 0.1 microM phenylephrine with a concomitant decrease in MLC phosphorylation. Incubation with IL-1 for 3 h or longer decreased alpha-smooth muscle actin and increased gamma-actin isoform, with no change in beta-nonmuscle actin or myosin isozyme content. These results suggest that IL-1 inhibition of a vascular smooth muscle contraction may be due to a decrease in activator calcium, which may account for the resultant decrease in MLC phosphorylation. These results also indicate that IL-1 significantly affects contractile protein content, enhancing gamma-actin isoforms and decreasing the vascular smooth muscle specific alpha-isoactin.
Trinkle
L A
LA
Bockus Research Institute, Graduate Hospital, Philadelphia, Pennsylvania 19146.
Beasley
D
D
Moreland
R S
RS
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects*; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D009218:Myosins / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D013312:Stress, Physiological / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects*
D000199:Actins; D007375:Interleukin-1; D009218:Myosins