Effects of norepinephrine on lung liquid production by in vitro lungs from fetal guinea pigs

Can J Physiol Pharmacol. Oct-Nov 1998;76(10-11):967-74. doi: 10.1139/cjpp-76-10-11-967.

Abstract

Lungs from near-term fetal guinea pigs (61 +/- 2 days of gestation) were supported in vitro for 3 h; lung liquid production was monitored by a dye dilution method. Untreated control preparations produced fluid at 1.38 +/- 0.30 mL x kg(-1) body weight x h(-1), with no significant change (ANOVA; regression analysis); those given 1.24 x 10(-9) or 1.24 x 10(-8) M norepinephrine during the middle hour showed no significant change, but those given concentrations between 5.24 x 10(-8) and 1.24 x 10(-5) M all showed significant reductions or fluid reabsorption (based on 42 fetuses). The responses showed a linear relationship with the log concentration (r = 0.97). They appeared to involve alpha-adrenoreceptors, since responses to 10(-7) M norepinephrine were unaffected by 10(-6) M propranolol, but those to 10(-7) and 1.24 x 10(-6) M norepinephrine were abolished by 10(-6) and 1.78 x 10(-5) M phentolamine, respectively (based on 48 fetuses). Activation was through alpha2-adrenoreceptors, since responses to 10(-7) and 10(-5) M norepinephrine were abolished by 10(-4) M yohimbine, but not by 10(-5) M prazosin (based on 60 fetuses). The results show that norepinephrine is able to reduce lung liquid production when at plasma levels present at birth, and that it can produce reabsorption; unlike epinephrine, there was no reduction in responses at high concentrations. This work reintroduces a neglected factor, norepinephrine, into possible controls of lung liquid reabsorption, and opens up the potential for neural controls.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic alpha-1 Receptor Antagonists
  • Adrenergic alpha-2 Receptor Antagonists
  • Adrenergic alpha-Agonists / pharmacology*
  • Adrenergic alpha-Antagonists / pharmacology
  • Adrenergic beta-Antagonists / pharmacology
  • Animals
  • Body Fluids / drug effects*
  • Body Fluids / metabolism
  • Dose-Response Relationship, Drug
  • Female
  • Fetus
  • Guinea Pigs
  • In Vitro Techniques
  • Lung / drug effects*
  • Lung / metabolism
  • Norepinephrine / pharmacology*
  • Phentolamine / pharmacology
  • Prazosin / pharmacology
  • Pregnancy
  • Propranolol / pharmacology
  • Statistics as Topic
  • Yohimbine / pharmacology

Substances

  • Adrenergic alpha-1 Receptor Antagonists
  • Adrenergic alpha-2 Receptor Antagonists
  • Adrenergic alpha-Agonists
  • Adrenergic alpha-Antagonists
  • Adrenergic beta-Antagonists
  • Yohimbine
  • Propranolol
  • Norepinephrine
  • Prazosin
  • Phentolamine