A simple method for sampling murine pulmonary and cardiac tissues for analysis of cyclic nucleotide levels.

A simple method for the rapid removal and freezing of mouse cardiac and pulmonary tissues is described. Samples thus obtained were judged to be suitable for valid estimation of in vivo levels of cyclic AMP and cyclic GMP based on the following findings: (a) the samples could be obtained and frozen in the very short time period of a few seconds; (b) no indication of adverse effects of the collection procedure was found upon examination of chemical indicators of energy metabolism; (c) the apparent rates of change of cyclic AMP and cyclic GMP levels during the first seconds after tissue isolation could produce small, but acceptable errors; and (d) dose-dependent elevations of pulmonary cAMP levels consistent with known effects in vitro were found after in vivo administration of isoproternol.