Locally injected dexmedetomidine induces vasoconstriction via peripheral α-2A adrenoceptor subtype in guinea pigs.
OBJECTIVE
Recent research shows that locally injected dexmedetomidine enhances the local anesthetic potency of lidocaine via the α-2A adrenoceptor subtype in guinea pigs. However, little is known about the effect of locally injected dexmedetomidine on the peripheral vascular response. This study aimed to evaluate the effect of locally injected dexmedetomidine on the peripheral vascular response, measuring skin blood flow in the injected area in guinea pigs.


METHODS
Dexmedetomidine was intracutaneously injected at a volume of 0.1 mL into the backs of guinea pigs, and further injected combined with yohimbine, a selective antagonist of α-2 adrenoceptors, or prazosin, a selective antagonist of α-1 adrenoceptors and an antagonist of both α-2B and α-2C adrenoceptor subtypes. Skin blood flow was measured until 60 minutes after injection using a laser-Doppler flowmeter. Furthermore, systemic arterial blood pressure and pulse of the guinea pigs were monitored via a catheter inserted into the carotid artery throughout every experiment.


RESULTS
Dexmedetomidine at a concentration of 1 μM significantly decreased the skin blood flow in a dose-dependent manner with no changes in the mean blood pressure and pulse. Yohimbine completely antagonized the effect of dexmedetomidine, but prazosin did not.


CONCLUSIONS
The results reveal that locally injected dexmedetomidine at a concentration of 1 μM induced peripheral vasoconstriction without a systemic cardiovascular response via the peripheral α-2A adrenoceptor subtype.
From the *Department of Dental Anesthesiology and Special Care Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences; †Department of Dental Anesthesiology, Okayama University Hospital; and ‡Dental Clinic, Okayama Kyoritsu General Hospital, Okayama, Japan.
Akiko
A
Yabuki
Hitoshi
H
Higuchi
Tatsushi
T
Yoshitomi
Yumiko
Y
Tomoyasu
Minako
M
Ishii-Maruhama
Shigeru
S
Maeda
Takuya
T
Miyawaki
D058647:Adrenergic alpha-2 Receptor Agonists / Q000008:administration & dosage*; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D020927:Dexmedetomidine / Q000008:administration & dosage*; D006168:Guinea Pigs; D007279:Injections, Subcutaneous; D008297:Male; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology*
D058647:Adrenergic alpha-2 Receptor Agonists; D018341:Receptors, Adrenergic, alpha-2; D020927:Dexmedetomidine