Ghrelin is an endocrine regulatory peptide with multiple functions including cardioprotective
effects. It is produced in various tissues among others in the myocardium. Pericardial
fluid has been proven to be a biologically active compartment of the heart that communicates
with the myocardial interstitium. Thus, pericardial level of certain agents may reflect
their concentration in the myocardium well. In our study we measured acylated (active)
and total (acylated and non-acylated) pericardial and plasma ghrelin levels of patients
with ischemic and non-ischemic heart disease. Pericardial fluid and plasma samples
were obtained from patients with coronary artery disease (ISCH, n=54) or valvular
heart disease (VHD, n=41) undergoing cardiac surgery. Acylated pericardial ghrelin
concentrations were found to be significantly higher in patients with ischemic heart
disease (ISCH vs. VHD, 32+/-3 vs. 16+/-2pg/ml, p<0.01), whereas plasma levels of the
peptide showed no difference between patient groups. Pericardial-to-plasma ratio,
an index abolishing systemic effects on local ghrelin level was also significantly
higher in ISCH group for both acylated and total ghrelin. Plasma total ghrelin showed
negative correlation to BMI, plasma insulin and insulin resistance index HOMA-A. Pericardial
acylated and total ghrelin concentrations were negatively correlated with posterior
wall thickness (R=-0.31, p<0.05 and R=-0.35, p<0.01, respectively). Plasma insulin
concentration and HOMA-A showed significant negative correlation with pericardial
ghrelin levels. In conclusion, increased pericardial active ghrelin content and higher
pericardial-to-plasma ghrelin ratio were found in ischemic heart disease as compared
to non-ischemic patients suggesting an increased ghrelin production of the chronically
ischemic myocardium. According to our results, pericardial ghrelin content is negatively
influenced by left ventricular hypertrophy and insulin resistance.
