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Canadian Journal of Anesthesia

, Volume 51, Issue 10, pp 979–985 | Cite as

The vascular relaxing effects of sevoflurane and isoflurane are more important in hypertensive than in normotensive rats

  • Jingui Yu
  • Koji Ogawa
  • Yasuyuki Tokinaga
  • Shizue Iwahashi
  • Yoshio Hatano
General Anesthesia

Abstract

Purpose

The vascular response to anesthetics is altered in hypertensive patients since the functional and structural integrities of vascular smooth muscle and endothelium are deranged. The effects of anesthetics on angiotensin II (Ang ll)-induced changes in vascular tone are not well understood. We investigated the effects of sevoflurane and isoflurane on Ang II-induced vasoconstriction in spontaneously hypertensive rats (SHR).

Methods

The dose-dependent effects of sevoflurane and isoflurane on the Ang II-induced contraction of aortic rings, in the presence and absence of an intact endothelium, were investigated in normotensive Wistar-Kyoto rats (WKY) and SHR and compared using isometric force transducers.

Results

Ang II (10−9-10−6 M) induced a similar transient phasic contraction of endothelium-intact rings from the two rat strains in a dose-dependent manner. Removal of the endothelium augmented the Ang II-elicited phasic contraction, to a greater extent in the SHR group than in the WKY group. Sevoflurane and isoflurane (1–3 minimum alveolar concentration) concentration-dependently inhibited the Ang II-induced contraction of endothelium-intact rings from WKY; an effect that was greatly enhanced following removal of the endothelium. Agreater degree of attenuation of the Ang II-induced contraction of both endothelium-intact and -denuded rings by the two anesthetics was observed in the SHR group. The inhibitory effects of isoflurane on the Ang II-induced contraction of aortic rings from both strains appeared to be stronger than that of sevoflurane at equipotent concentrations.

Conclusion

Our finding that the inhibitory effects of isoflurane and sevoflurane on Ang II-induced vasoconstriction are enhanced in SHR may, at least in part, account for the anesthesia-induced systemic hypotension frequently seen in hypertensive patients.

Keywords

Isoflurane Sevoflurane Aortic Ring Minimum Alveolar Concentration Tonic Contraction 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Les effets vasculaires décontractants du sévoflurane et de l’isoflurane sont plus importants chez les rats hypertendus comparés aux normotendus

Résumé

Objectif

La réponse vasculaire aux anesthésiques est modifiée chez les patients hypertendus, car l’intégrité fonctionnelle et structurale des muscles lisses vasculaires et de l’endothélium est perturbée. Les effets des anesthésiques sur les changements de tonus vasculaire induits par l’angiotensine II (Ang II) ne sont pas très bien compris. Nous avons exploré les effets du sévoflurane et de l’isoflurane sur la vasoconstriction induite par l’Ang II chez des rats spontanément hypertendus (PSH).

Méthode

Les effets reliés à la dose du sévoflurane et de l’isoflurane sur la contraction d’anneaux aortiques induite par l’Ang II, en présence et en l’absence d’un endothélium intact, ont été examinés chez des rats Wistar-Kyoto (WKY) normotendus et RSH et comparés en utilisant des transducteurs de force isométrique.

Résultats

L’Ang II (10−9-10−6 M) a induit une contraction phasique transitoire, dépendante de la dose, des anneaux intacts d’endothélium prélevés chez les deux souches de rats. Le retrait de l’endothélium a augmenté la contraction phasique induite par l’Ang II, davantage dans le groupe RSH que dans le groupe WKY. Le sévoflurane et l’isoflurane (de concentration alvéolaire minimale de 1–3) ont inhibé la contraction induite pas l’Ang II des anneaux intacts d’endothélium de WKY en fonction de la concentration. C’est un effet qui a été grandement accru à la suite du retrait de l’endothélium. Une plus importante atténuation de la contraction induite par l’Ang II des anneaux dénudés et des anneaux intacts d’endothélium par les deux anesthésiques a été observée dans le groupe RSH. Les effets inhibiteurs de l’isoflurane sur la contraction des anneaux aortiques des deux souches induite par l’Ang II sont apparus plus prononcés que ceux du sévoflurane pour des concentrations équivalentes.

Conclusion

Notre résultat voulant que les effets inhibiteurs de l’isoflurane et du sévoflurane sur la vasoconstriction induite par l’Ang II soient accrus chez les RSH peut, au moins en partie, expliquer l’hypotension générale induite par l’anesthésie observée chez les patients hypertendus.

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Copyright information

© Canadian Anesthesiologists 2004

Authors and Affiliations

  • Jingui Yu
    • 1
  • Koji Ogawa
    • 2
  • Yasuyuki Tokinaga
    • 1
  • Shizue Iwahashi
    • 1
  • Yoshio Hatano
    • 1
  1. 1.Department of AnesthesiologyWakayama Medical UniversityWakayama CityJapan
  2. 2.Department of Surgical Operating CenterWakayama Medical UniversityWakayama CityJapan

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