Effect of MK-467 on organ blood flow parameters detected by contrast-enhanced ultrasound in dogs treated with dexmedetomidine

Objective To evaluate the dexmedetomidine-induced reduction in organ blood flow with quantitative contrast-enhanced ultrasound (CEUS) method and to observe the influence of MK-467 on such reduction. Study design Randomized cross-over study. Animals Six adult purpose-bred laboratory beagle dogs (mean body weight 15.3 +/- 1.9 kg). Methods Contrast-enhanced ultrasound was performed on six conscious healthy laboratory beagles. The animals on separate occasions underwent three treatments: awake without any medication (CTRL), dexmedetomidine 10 mu g kg(-1) (DEX) and DEX + MK-467 500 mu g kg(-1) (DMK) intravenously (IV). The kidney (10-15 minutes post-treatment), spleen (25-30 minutes post-treatment), small intestine (40-45 minutes post-treatment) and liver (50-55 minutes post-treatment) were examined with CEUS. A time curve was generated and the following perfusion parameters were analysed: arrival time (AT), time to peak from injection (TTPinj), peak intensity (PI) and wash-in rate (Wi). In addition to CEUS, renal glomerular filtration rate was indirectly estimated by the rate of iohexol elimination. Results AT and TTPinj were significantly higher for DEX than for CTRL in all studied organs. The same parameters were significantly higher for DEX than for DMK in the kidney, spleen and small intestine. PI was significantly lower for DEX than for CTRL or DMK in the kidney. Wi was significantly lower for DEX than for CTRL or DMK in the kidney and significantly lower than for CTRL only in the small intestine. Plasma concentration of iohexol was significantly higher after DEX than CTRL administration. Conclusions Contrast-enhanced ultrasound was effective in detecting DEX-induced changes in blood flow. MK-467 attenuated these changes.