THE TRABECULA CULTURE SYSTEM - A NOVEL TECHNIQUE TO STUDY CONTRACTILEPARAMETERS OVER A MULTIDAY TIME PERIOD

In the intact heart, various triggers induce alterations in gene expre ssion that impact on contractile function. Because changes in gene exp ression reflect altered protein expression patterns after 12-48 h, we developed a system in which intact twitching cardiac trabeculae can be studied for multiday periods. Right ventricular trabeculae from pento barbital sodium-anesthetized rabbits were mounted in a sterile, closed muscle chamber. Over the first 48 h, developed force (F-dev) did not significantly change: 102.3 and 98.9% of the initial F-dev was observe d after 24 and 48 h, respectively (n = 8). Also, neither diastolic for ce, time from peak to 50% relaxation (RT50), nor protein synthesis mea sured by a [H-3]leucine incorporation assay changed significantly over time. Contractile response after >48 h to an increase in extracellula r calcium concentration (1.8 to 2.5 mM; F-dev increased 43.5%, n = 2) or to 1 mu M isoproterenol (F-dev increased 138.6% and RT50 decreased 34.9%, n = 2) was similar to those observed in freshly dissected prepa rations. In conclusion, this system can investigate contractile functi on of multicellular preparations under well-defined physiological cond itions after events that alter gene and consequent protein expression.