title: Vasomotor responses in the isolated perfused external and internal carotid vascular beds of the rat.
abstract: 1. The external (ECB) or the internal (ICB) carotid vascular beds of the rat were isolated and perfused with Krebs-Henseleit solution at constant flow (1 ml/min). Changes in perfusion pressure (PP) were recorded after cervical sympathetic stimulation and after the administration of norepinephrine (NE) and serotonin (5-HT). 2. Sympathetic stimulation induced an increase in PP (vasoconstriction) in both vascular beds, however, this effect was significantly higher in the ECB than in the ICB. 3. Exogenous NE also induced a significantly higher contractile response in the ECB. 4. Prazosin (10(-8) M) significantly inhibited the response to sympathetic stimulation and to NE both in the ECB and in the ICB, but yohimbine (10(-7) M) had no effect, suggesting that the vasoconstriction was mainly due to the activation of alpha 1-adrenoceptors. 5. 5-HT induced a contractile response both in the ECB and the ICB. In contrast with the response to NE, the contraction induced by 5-HT in the ICB was significantly higher than in the ECB. 6. Ketanserine (10(-8) M) antagonised both responses, indicating the involvement of 5-HT2 receptors. 7. The contractile effect of 5-HT in the ECB was significantly enhanced by a subthreshold sympathetic stimulation that did not modify the PP by itself. This effect was not seen in the ICB. 8. The differential perfusions of the ECB or the ICB demonstrated a different reactivity of ECB and ICB, both to sympathetic stimulation and to the administration of exogenous NE or 5-HT. 9. Furthermore, the response to 5-HT in the ECB was modulated by a subthreshold sympathetic stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiopathology, Vargas School of Medicine, Faculty of Medicine Central University of Venezuela, Caracas.
authors.forename: J V
authors.initials: JV
authors.lastname: Vásquez
authors.forename: G
authors.initials: G
authors.lastname: Pinardi
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002339:Carotid Arteries / Q000187:drug effects* / Q000294:innervation; D002342:Carotid Artery, External / Q000187:drug effects / Q000294:innervation; D002343:Carotid Artery, Internal / Q000187:drug effects / Q000294:innervation; D005260:Female; D066298:In Vitro Techniques; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000502:physiology; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D015016:Yohimbine; D012701:Serotonin; D007650:Ketanserin; D009638:Norepinephrine; D011224:Prazosin