Up-regulation of inositol 1,4,5 trisphosphate receptor expression in atrial tissue in patients with chronic atrial fibrillation.

OBJECTIVES: We examined whether patients with atrial fibrillation (AF) have alterations in atrial inositol 1,4,5 trisphosphate receptors (IP3 receptors). BACKGROUND: Abnormal intracellular Ca2+ homeostasis occurs in chronic AF. The intracellular Ca2+ concentration is regulated by ryanodine and IP3 receptors. We recently reported alterations in ryanodine receptors in atrial tissue from patients in chronic AF. METHODS: We analyzed IP3 receptor expression in the right atrial myocardium from 13 patients with mitral valvular disease (MVD) with AF (MVD/AF), five patients with MVD who had normal sinus rhythm (MVD/NSR) and eight control patients with NSR (tissue obtained during coronary artery bypass surgery). Hemodynamic and echocardiographic data were obtained preoperatively, and an immunohistochemical study was performed on atrial tissue. RESULTS: The relative expression level of IP3 receptor protein was significantly greater in MVD/AF (0.75 +/- 0.26) than it was in MVD/NSR (0.42 +/- 0.13, p < 0.01), and both were significantly above control (0.14 +/- 0.08). The relative expression level of IP3 receptor messenger RNA was significantly greater in the MVD/AF group (0.028 +/- 0.008) than it was in the control group (0.015 +/- 0.004, p < 0.01), but patients with MVD/AF did not differ from patients with MVD/NSR (0.020 +/- 0.006). The relative expression levels of IP3 receptor protein and messenger RNA were higher in patients with left atrial dimension > or = 40 mm, pulmonary capillary wedge pressure > or = 10 mm Hg and right atrial pressure > or = 5 mm Hg. Inositol 1,4,5 trisphosphate receptors were over-expressed in the cytosol and at the nuclear envelope of atrial myocytes in MVD. CONCLUSIONS: Since chronic mechanical overload of the atrial myocardium increased IP3 receptor expression, especially in patients with chronic AF, up-regulation of IP3 receptors may be important in modulating intracellular Ca2+ homeostasis and initiating or perpetuating AF.

Toxic shock-like syndrome resembling phlegmasia cerulea dolens.

A case of a 71-year-old Japanese woman with toxic shock-like syndrome is reported. She was admitted to the hospital because of swelling of the right leg. On admission, right lower leg was erythematous and swollen with an erosive lesion. On the second day, she rapidly fell into shock. Phlegmasia cerulea dolens caused by massive iliofemoral venous thrombosis was suspected because she had a history of deep venous thrombosis. But deep venous thrombus was not detected by venography at emergent surgery for thromboembolectomy. She died 38 hours after admission despite maximal supportive therapy. Group A beta-hemolytic streptococci were isolated from blood culture and soft tissue after the patient died.