The effects of phentolamine and propranolol on contractural responses of guinea-pig superior mesenteric-portal vein to adrenaline and isoprenaline were investigated. Phentolamine was capable of completely abolishing the response to adrenaline and to isoprenaline while propranolol had no effect on responses to either agonist. It is suggested that Alpha receptors are the only type of adrenoceptor involved in adrenergic control of contraction of this vein and that isoprenaline is capable of stimulating these receptors.
* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.