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Age and region‐dependent contraction to α‐adrenoceptor agonists in rat and guinea‐pig isolated trachea
Author(s) -
Preuss Janet M. H.,
Rigby Paul J.,
Goldie Roy G.
Publication year - 1998
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0701765
Subject(s) - contraction (grammar) , guinea pig , muscle contraction , endocrinology , medicine , biology , chemistry
The influence of age and of region on α‐adrenoceptor‐mediated contraction to (−)‐adrenaline and (−)‐noradrenaline was examined in rat (4–136 weeks) and guinea‐pig (2–156 weeks) isolated tracheal ring preparations with particular emphasis on the early (up to 12 weeks) maturation phase. In rat tracheal rings, significant regional variation was observed with respect to maximal (−)‐adrenaline‐induced contraction, such that the greatest activity was seen in ring preparations from the laryngeal end of the trachea. Tracheal rings from the carinal end responded very poorly or were unresponsive to (−)‐adrenaline, depending on animal age. These regional differences were seen across the age range. The potencies of (−)‐adrenaline and (−)‐noradrenaline remained unchanged with respect to animal age, but the maximum contractile tension that developed in response to these agonists increased with increasing animal age in all regions of the trachea. In guinea‐pig isolated tracheal tissue, maximum contractile responses (E max ) to (−)‐adrenaline and (−)‐noradrenaline remained unchanged with increasing animal age. In addition, there was no evidence for a region‐dependence in the responsiveness of tracheal tissue to α‐adrenoceptor‐mediated contraction in this species. In both guinea‐pig and rat isolated tracheal tissue, α‐adrenoceptor‐mediated contraction appeared to involve the activation of α 1 ‐adrenoceptors.British Journal of Pharmacology (1998) 123 , 1541–1548; doi: 10.1038/sj.bjp.0701765