theophylline article 42 Theophylline 22 nonhuman 20 priority journal 20 Animal 14 Animals 14 Cyclic AMP 14 unclassified drug 14 animal 12 cyclic AMP 12 enzyme activity 12 Male 10 Support, Non-U.S. Gov't 10 controlled study 10 isobutylmethylxanthine 10 muscle 10 papaverine 10 phosphodiesterase inhibitor 10 signal transduction 10 1-Methyl-3-isobutylxanthine 8 3',5'-Cyclic-Nucleotide Phosphodiesterase 8 Adenine Nucleotides 8 Glucosyltransferases 8 Muscles 8 Na(+)-K(+)-Exchanging ATPase 8 Phosphoric Monoester Hydrolases 8 Rats 8 Signal Transduction 8 adenine nucleotide 8