Effect of phorbol ester on contractile response of aorta from endotoxic rats.
The influence of phorbol ester on the isometric contractile response of aorta from endotoxic rats was examined. In endotoxic rat aorta, the contractile responses to KCl and phorbol 12,13-dibutyrate (PDBu) were both remarkably diminished, compared to those in control rat aorta. Preincubation with PDBu augmented the aortic contractile response to KCl in both control and endotoxic rats. This augmentative effect of PDBu was significantly more pronounced in endotoxic rats than in controls. When the contractile response to 80 mM KCl reached a plateau after PDBu pretreatment, addition of 5 mM CaCl2 (final concentration) to the organ bath completely reversed the diminished contractile response of endotoxic rat aorta to the control level. These results suggest that the hyporesponsiveness of endotoxic rat aorta to KCl may be caused by decreases in both protein kinase C mediated response and calcium sensitivity of vascular smooth muscle cells.
Wakabayashi
I
I
Second Department of Internal Medicine, Hyogo College of Medicine, Japan.
Kakishita
E
E
Hatake
K
K
Hishida
S
S
Nagai
K
K
D000818:Animals; D001011:Aorta; D004731:Endotoxins / Q000494:pharmacology*; D004926:Escherichia coli; D007537:Isometric Contraction / Q000187:drug effects*; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D015240:Phorbol 12,13-Dibutyrate; D010703:Phorbol Esters / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D004731:Endotoxins; D010703:Phorbol Esters; D015240:Phorbol 12,13-Dibutyrate; D011189:Potassium Chloride