title: Caffeine effect on myocardial mechanical function in the neonatal rabbit heart.
abstract: The effects of 20 mM caffeine on myocardial mechanical function were studied in isolated, arterially perfused cardiac preparations of newborn and adult rabbits. Caffeine caused a significant increase in the maximal rate of tension development in the adult (141% of control) but not in the newborn (111%). The resting tension increased significantly in both age groups. However, the increase in the adult (245% of control) was also significantly greater than in the newborn (132%). At the points of maximum effect, caffeine perfusion in the newborn resulted in a decrease in the maximal rate of relaxation (29% of control) and an increase in the half relaxation time (144% of control) that were significantly greater than they were in the adult (41% and 103%, respectively). These data show distinct age-related differences in the effects of caffeine on myocardial mechanical function. These differences may be due to maturational changes that occur in the sarcoplasmic reticulum and T tubule system of the rabbit heart. However, maturational changes in the activity of phosphodiesterase and/or the sympathetic nervous system may play a role.
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D009200:Myocardial Contraction / Q000187:drug effects; D010477:Perfusion; D011817:Rabbits; D012508:Sarcolemma / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013997:Time Factors
chemical_list: D002110:Caffeine; D002118:Calcium