These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Postnatal development of vascular beta-adrenoceptor-mediated responses and the increase in the adrenaline content of the adrenal gland have a parallel time course.
    Author: Paiva MQ, Moura D, Vaz-da-Silva MJ, Guimarães S.
    Journal: Naunyn Schmiedebergs Arch Pharmacol; 1994 Jul; 350(1):28-33. PubMed ID: 7935851.
    Abstract:
    The present study was undertaken to analyse the relationship between postnatal development of vascular beta 2-adrenoceptor-mediated responses and the content of adrenaline in the adrenal gland and its concentration in plasma. Dog saphenous vein tissue from newborn, two-weeks old and adult animals were either preloaded with 3H-noradrenaline (or 3H-adrenaline) to study prejunctional beta-adrenoceptor-mediated effects or mounted in organ baths to determine isoprenaline-induced relaxation of preparations contracted by phenylephrine to about 65% of the maximum. The adrenal glands and samples of blood from the same animals were taken for estimation of adrenaline and noradrenaline. At birth, there were no beta-adrenoceptor-mediated effects pre- or postjunctionally. At two weeks, while the results at the prejunctional level were not significantly different from those obtained in newborns, at the postjunctional level there was a relaxant response to isoprenaline, which antagonised about 35% of the previous contraction to 1.75 mumol.l-1 phenylephrine. In adults, isoprenaline (50 nmol.l-1) increased by 24% tritium overflow evoked by electrical stimulation of tissues preloaded with 3H-noradrenaline but not that of tissues preloaded with 3H-adrenaline. On the other hand, propranolol (1 mumol.l-1) reduced by 21% the overflow of tritium evoked by electrical stimulation of tissues preloaded with 3H-adrenaline but not that of tissues preloaded with 3H-noradrenaline; postjunctionally, the maximal response to isoprenaline antagonised 70% of the previous contraction to 1.75 mumol.l-1 phenylephrine.(ABSTRACT TRUNCATED AT 250 WORDS)
    [Abstract] [Full Text] [Related] [New Search]