A–C: urinary excretion rates of 2′,3′-cAMP, 2′-AMP, and 3′-AMP before and during intravenous infusion of 2′,3′-cAMP (0.3 µmol·kg−1·min−1) into 2′,3′-cyclic nucleotide 3′-phosphodiesterase (CNPase) wild-type (CNPase+/+) and knockout (CNPase−/−) mice. D: urinary 2′-AMP-to-3′-AMP ratio during infusion of 2′,3′-cAMP into CNPase+/+ and CNPase−/− mice. aP < 0.05 vs. basal (0) values, bP < 0.05 vs. corresponding value in CNPase+/+ mice [by repeated-measures 2-factor (RM-2F) ANOVA]. Because the y-axis scale captured the large effects of 2′,3′-cAMP infusions, basal (0) values are near or within the width of the x-axis. Values are means ± SE.