Potential paracrine role of the pericardium in the regulation of cardiac function.
OBJECTIVE
Both coronary and endocardial endothelium regulate cardiac contractile function via paracrine pathways. We investigated whether pericardial fluid (PF) and pericardial mesothelial cells (PMC) could exert a similar paracrine action.


METHODS
Both PF and PMC were extracted from sheep pericardial space. Endothelin-1, prostaglandins and atrial natriuretic factor were measured in PF in vivo. In the other hand, PMC were grown on T-75 flasks and microcarrier beads to investigate endothelin-1, nitric oxide and prostaglandin pathways in vitro. In addition, effects of PF and PMC effluent were tested on adult rat cardiac myocyte contraction in vitro.


RESULTS
In vitro, cultured PMC expressed endothelin-1 mRNA but not the endothelial nitric oxide synthase III, and released endothelin-1 and prostaglandins. Both PF and cultured PMC superfusate induced a potent, rapidly reversible decrease in the shortening of isolated rat cardiac myocytes. This effect was not associated with changes in intracellular calcium. In vivo, prostaglandins, atrial natriuretic factor and endothelin were present in PF. A greater concentration of atrial natriuretic factor was present in PF than in serum, suggesting molecular diffusion from the myocardium to PF. Preliminary results show that the instillation of vasoactive agents into the pericardial space of dogs rapidly alter coronary and systemic vascular tone, consistent with a molecular diffusion of these substances from PF into the myocardium and circulation.


CONCLUSIONS
In addition to its mechanical role, the pericardium may contribute to the integration and the regulation of cardiovascular function via a paracrine mechanism.
Mebazaa
A
A
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins Medical Institutions, Baltimore, MD 21287-3711, USA. amebazaa.lariboisiere@invivo.edu
Wetzel
R C
RC
Dodd-o
J M
JM
Redmond
E M
EM
Shah
A M
AM
Maeda
K
K
Maistre
G
G
Lakatta
E G
EG
Robotham
J L
JL
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000032:analysis / Q000378:metabolism; D048429:Cell Size; D002478:Cells, Cultured; D004285:Dogs; D019332:Endothelin-1 / Q000032:analysis / Q000235:genetics; D004837:Epinephrine / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D005122:Exudates and Transudates / Q000737:chemistry / Q000502:physiology; D005260:Female; D015151:Immunoblotting; D007150:Immunohistochemistry; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000032:analysis; D052250:Nitric Oxide Synthase Type III; D005996:Nitroglycerin / Q000494:pharmacology; D019899:Paracrine Communication; D010496:Pericardium / Q000737:chemistry / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D011453:Prostaglandins / Q000032:analysis / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012756:Sheep; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D019332:Endothelin-1; D011453:Prostaglandins; D012333:RNA, Messenger; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009320:Atrial Natriuretic Factor; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D005996:Nitroglycerin; D004837:Epinephrine