Interactions Between Cardioregulatory Agents in the Pericardium

The general consensus on the §physiological role of the pericardial fluid assigns §it the function of providing continuous lubrication §for the epicardium of the beating heart. In addition §to those constituents which serve a hydration §function, the pericardial fluid also contains a §large number of active endogenous agents such as §endothelin-1, adenine nucleosides, catecholamines, §natriuretic peptides, and angiotensin II. More §importantly, the §concentrations of these regulatory factors are §several magnitudes higher in the pericardial fluid §than in the plasma, reflecting their derivation from §the myocardial tissue and suggesting a teleological §role for the pericardial space as a functionally §distinct compartment with a potential function in §cardiac regulation. Our investigations of the §composition and dynamic changes of the pericardial §fluid provide a remarkable opportunity to study §these interactions within in vivo systems because of §two critical principles: these agents exert their §effects through the interstitial space and §pericardial fluid composition portrays the changes §in myocardial function.