Effects of norepinephrine on lung liquid production by in vitro lungs from fetal guinea pigs.
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.
Doe
S
S
Department of Obstetrics and Gynecology, The University of British Columbia, Vancouver, Canada.
Woods
B
B
Perks
A M
AM
D058668:Adrenergic alpha-1 Receptor Antagonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001826:Body Fluids / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D005333:Fetus; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011247:Pregnancy; D011433:Propranolol / Q000494:pharmacology; D013223:Statistics as Topic; D015016:Yohimbine / Q000494:pharmacology
D058668:Adrenergic alpha-1 Receptor Antagonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D015016:Yohimbine; D011433:Propranolol; D009638:Norepinephrine; D011224:Prazosin; D010646:Phentolamine