Reduced calcium responsiveness characterizes contractile dysfunction following coronary microembolization.
OBJECTIVE
We addressed calcium responsiveness in microembolized myocardium at 6 h after coronary microembolization (ME).


RESULTS
In anesthetized pigs calcium responsiveness was determined as the increase of a myocardial work index (WI; LV pressure development vs. wall thickening) in response to a graded intracoronary infusion of CaCl(2) at baseline and at 6 h after ME or placebo, respectively. At baseline, CaCl(2 )infusion increased WI in both groups (ME: 296 +/- 22 to 468 +/- 47 mmHg*mm; placebo: 324 +/- 24 to 485 +/- 38 mmHg*mm; mean +/- SEM). At 6 h after ME, WI was decreased by 159 +/- 16 mmHg*mm (P < 0.05 vs. baseline) and remained reduced at any calcium concentration, whereas it was unchanged with placebo. The calcium concentration in coronary blood necessary to achieve the half maximal increase in WI remained unchanged from baseline to 6 h and did not differ between placebo and ME.


CONCLUSIONS
The ME-induced myocardial dysfunction is not related to an altered calcium sensitivity, but is characterized by a reduced maximal contractile force.
Institute of Pathophysiology, University School of Medicine, Essen, Germany.
Andreas
A
Skyschally
Petra
P
Gres
Patrick
P
van Caster
Anita
A
van de Sand
Kerstin
K
Boengler
Rainer
R
Schulz
Gerd
G
Heusch
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D054059:Coronary Occlusion / Q000503:physiopathology*; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004617:Embolism / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects* / Q000502:physiology; D009206:Myocardium / Q000378:metabolism; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D013552:Swine; D013556:Swine, Miniature; D013997:Time Factors; D014335:Tropomyosin / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D014335:Tropomyosin; D014409:Tumor Necrosis Factor-alpha; D002118:Calcium