title: Blunted increase in plasma adenosine levels following dipyridamole stress in dilated cardiomyopathy patients.
abstract: BACKGROUND
  Heart failure is characterized by chronically increased adenosine levels, which are thought to express a protective anti-heart failure activation of the adenosinergic system. The aim of the study was to assess whether the activation of adenosinergic system in idiopathic dilated cardiomyopathy (IDC) can be mirrored by a blunted increase in plasma adenosine concentration following dipyridamole stress, which accumulates endogenous adenosine.
  
  
  METHODS
  Two groups were studied: IDC patients (n = 19, seven women, mean age 60 +/- 12 years) with angiographically confirmed normal coronary arteries and left ventricular ejection fraction <35%; and normal controls (n = 15, six women, mean age 68 +/- 5 years). Plasma adenosine was assessed by high-performance liquid chromatography methods in blood samples from peripheral vein at baseline and 12 min after dipyridamole infusion (0.84 mg kg-1 in 10 min).
  
  
  RESULTS
  At baseline, IDC patients showed higher plasma adenosine levels than controls (276 +/- 27 nM L-1 vs. 208 +/- 48 nM L-1, P < 0.001). Following dipyridamole, IDC patients showed lower plasma adenosine levels than controls (322 +/- 56 nM L-1 vs. 732 +/- 250 nM L-1, P < 0.001). The dipyridamole-induced percentage increase in plasma adenosine over baseline was 17% in IDC and 251% in controls (P < 0.001). By individual patient analysis, 18 IDC patients exceeded (over the upper limit) the 95% confidence limits for normal plasma adenosine levels at baseline, and all 19 exceeded (below the lower limit) the 95% confidence limits for postdipyridamole plasma adenosine levels found in normal subjects.
  
  
  CONCLUSIONS
  Patients with IDC have abnormally high baseline adenosine levels and--even more strikingly--blunted plasma adenosine increase following dipyridamole infusion. This is consistent with a chronic activation of the adenosinergic system present in IDC, which can be measured noninvasively in the clinical theatre.
authors.affiliation: Institute of Clinical Physiology of Consiglio Nazionale delle Ricerche, Pisa, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Laghi-Pasini
authors.forename: F
authors.initials: F
authors.lastname: Guideri
authors.forename: C
authors.initials: C
authors.lastname: Petersen
authors.forename: P E
authors.initials: PE
authors.lastname: Lazzerini
authors.forename: R
authors.initials: R
authors.lastname: Sicari
authors.forename: P L
authors.initials: PL
authors.lastname: Capecchi
authors.forename: E
authors.initials: E
authors.lastname: Picano
mesh_terms: D000241:Adenosine / Q000097:blood*; D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000097:blood* / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D004176:Dipyridamole; D025401:Echocardiography, Stress / Q000379:methods; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D004176:Dipyridamole; D000241:Adenosine