Article date: July 2017
By: Yan Wang, Quanhong Zhou, Bin Wu, Huixuan Zhou, Xiaoli Zhang, Wei Jiang, Li Wang, Aizhong Wang in Volume 174, Issue 13, pages 1984-2000
Background and Purpose
Exaggerated hypotension following administration of propofol is strongly predicted in patients with hypertension. Increased PKCs play a crucial role in regulating vascular tone. We studied whether propofol induces vasodilation by inhibiting increased PKC activity in spontaneously hypertensive rats (SHRs) and, if so, whether contractile Ca2+ sensitization pathways and filamentous–globular (F/G) actin dynamics were involved.
Experimental Approach
Rings of thoracic aorta, denuded of endothelium, from normotensive Wistar‐Kyoto (WKY) rats and SHR were prepared for functional studies. Expression and activity of PKCs in vascular smooth muscle (VSM) cells were determined by Western blot analysis and elisa respectively. Phosphorylation of the key proteins in PKC Ca2+ sensitization pathways was also examined. Actin polymerization was evaluated by differential centrifugation to probe G‐ and F‐actin content.
Key Results
Basal expression and activity of PKCβ2 and PKCθ were increased in aortic VSMs of SHR, compared with those from WKY rats. Vasorelaxation of SHR aortas by propofol was markedly attenuated by LY333531 (a specific PKCβ inhibitor) or the PKCθ pseudo‐substrate inhibitor. Furthermore, noradrenaline‐enhanced phosphorylation, and the translocation of PKCβ2 and PKCθ, was inhibited by propofol, with decreased actin polymerization and PKCβ2‐mediated Ca2+ sensitization pathway in SHR aortas.
Conclusion and Implications
Propofol suppressed increased PKCβ2 and PKCθ activity, which was partly responsible for exaggerated vasodilation in SHR. This suppression results in inhibition of actin polymerization, as well as that of the PKCβ2‐ but not PKCθ‐mediated, Ca2+ sensitization pathway. These data provide a novel explanation for the unwanted side effects of propofol.
DOI: 10.1111/bph.13797
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