Decrease in Vascular Resistance in the Isolated Canine Hindlimb After Graded Doses of Alfentanil, Fentanyl, and Sufentanil

Abstract

Under halothane anesthesia five dogs were prepared with both hindlimbs isolated from the systemic circulation to allow intermittent placement on extracorporeal perfusion at constant flow. One limb of each dog was surgically denervated. In this relatively anesthetic-free preparation, graded equivalent doses of alfentanil, fentanyl, and sufentanil were infused over 30 s, and vascular resistance was measured. Increasing opioid administration caused a progressive diminution in peripheral resistance. By the high dose level, alfentanil (500 micrograms/kg), fentanyl (50 micrograms/kg), and sufentanil (6 micrograms/kg) caused equal and significant decreases of 48%, 48%, and 44% in resistance, respectively. There was no difference among the opioids in effects on resistance at equivalent dosages. Neither pretreatment with naloxone nor denervation changed the response to the narcotics. We conclude that the three synthetic opioids produce vasodilation by direct action on the peripheral vascular smooth muscle.

Efeitos cardiovasculares e neuroendócrinos do butorfanol e da buprenorfina em cães anestesiados pelo desfluorano

“…Tal achado estaria relacionado à redução da resistência periférica total promovida pelo opióide, através de mecanismo de ação no sistema nervoso central (SNC), ou diretamente sobre a musculatura lisa dos vasos, como citado por White et al (1990). Já os anestésicos inalatórios halogenados, como o halotano, isofluorano ou desfluorano, tendem a reduzir a pressão arterial (PA) de modo relacionado à dose empregada.…”

Phosphatidylinositol responses are involved in the vascular effects of thiamylal and fentanyl

“…However, Karasawa et al 23 reported that pretreatment with naloxone had no effect on fentanylinduced relaxation of rat aortic rings. White et al 6 found, in dogs, that pretreatment with naloxone did not alter the vascular response to fentanyl. Makita et al 24 reported that naloxone did not affect the inhibitory effect of fentanyl on the NE-induced PI response in rat cerebral cortical prisms.…”

“…In humans, there is one report that fentanyl reduced the peripheral vascular resistance t9-21 and another that fentanyl had no effect." White et al 6 found, in dogs, that high-dose fentanyl (50 ~g-kg -~) caused a decrease in peripheral vascular resistance of 48% in the isolated hindlimb, and that pretreatment with denervation did not change the response to fentanyl. They concluded that fentanyl produced vasodilatation by direct action on the peripheral vascular smooth muscle.…”

“…Toda et al s reported that the contractile response of helically-cut strips of rabbit ascending aorta to transmural electrical stimulation was attenuated by fentanyl in a dose-dependent manner, and that fentanyl shifted the dose-response curve of the contraetile response of the aorta to norepinephrine (NE) to the right. White et al 6 reported that, in dogs with both hindlimbs isolated from the systemic circulation to allow extracorporeal perfusion at constant flow, increasing fentanyl administration caused a progressive diminution in peripheral resistance.…”

Hemogasometria e variáveis cardiopulmonares após administração do butorfanol em cães anestesiados pelo desfluorano sob ventilação espontânea

“…Todavia, esse parâmetro permaneceu estável ao longo de todo o período experimental, uma vez que não houve alteração das concentrações inspiradas do agente volátil. Entretanto, a adição do butorfanol causou diminuição das pressões arteriais, o que, de acordo com TYNER et al (1989), pode ser atribuído à redução da resistência periférica total (RPT) promovida pelo agente devido à ação do fármaco no sistema nervoso central, ou diretamente sobre a musculatura lisa dos vasos (WHITE et al, 1990). Ainda quanto às pressões arteriais, pode ter ocorrido efeito aditivo do desfluorano aos do opióide sobre a musculatura vascular, facilitando o relaxamento e propiciando esta diminuição de pressão (RODIG et al, 1997).…”