Effects of cAMP, its analogues, and forskolin on lung fluid production by in vitro lung preparations from fetal guinea pigs.
Lungs from fetal guinea pigs (62 +/- 1 days of gestation) were supported in vitro for 3 h and fluid production was determined by a dye dilution method, based on Blue Dextran 2000. Twenty untreated lungs produced fluid at 1.41 +/- 0.22 mL.kg-1 body weight.h-1, with no significant changes during later hours. Treatments with analogues of cAMP, cAMP, or forskolin during the middle hour reduced production significantly. Dibutyryl cAMP at 10(-3) M produced reabsorption (117.8 +/- 13.6% reduction, p less than 0.001, n = 10); at 10(-4) M it reduced production (77.3 +/- 11.0% fall, p less than 0.001, n = 10). 8-Bromo-cAMP appeared more effective; at 10(-4) M it caused slight reabsorption (109.0 +/- 8.9% reduction, p less than 0.001, n = 6) and at lower concentrations it decreased production (at 10(-6) M, 67.6 +/- 9.6% fall, p less than 0.001, n = 6; at 10(-7) M, 40.0 +/- 14.3% fall, p less than 0.001, n = 6). At high doses, cAMP itself produced similar effects (at 5 x 10(-3) M, 141.6 +/- 22.8% reduction, p less than 0.001, n = 6); at 10(-4) it was ineffective (n = 3). Forskolin at 10(-6) M induced the strongest reabsorptions seen (159.1 +/- 10.9% reduction, p less than 0.001, n = 6); at lower concentrations it reduced production (at 10(-8) M, 73.8 +/- 5.5% fall, p less than 0.001, n = 6; at 10(-9) M, 29.2 +/- 9.2% fall, p less than 0.05, n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)
Kindler
P M
PM
Department of Zoology, University of British Columbia, Vancouver, Canada.
Ziabakhsh
S
S
Perks
A M
AM
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001826:Body Fluids / Q000378:metabolism*; D003994:Bucladesine / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology*; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005260:Female; D005333:Fetus / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D011247:Pregnancy
D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D003994:Bucladesine; D000242:Cyclic AMP