The functional association between the sodium/bicarbonate cotransporter (NBC) and the soluble adenylyl cyclase (sAC) modulates cardiac contractility.

The soluble adenylyl cyclase (sAC) was identified in the heart as another source of cyclic AMP (cAMP). However, its cardiac physiological function is unknown. On the other hand, the cardiac Na+/HCO3- cotransporter (NBC) promotes the cellular co-influx of HCO3- and Na+. Since sAC activity is regulated by HCO3-, our purpose was to investigate the potential functional relationship between NBC and sAC in the cardiomyocyte. Rat ventricular myocytes were loaded with Fura-2, Fluo-3, or BCECF to measure Ca2+ transient (Ca2+i) by epifluorescence, Ca2+ sparks frequency (CaSF) by confocal microscopy, or intracellular pH (pHi) by epifluorescence, respectively. Sarcomere or cell shortening was measured with a video camera as an index of contractility. The NBC blocker S0859 (10 µM), the selective inhibitor of sAC KH7 (1 µM), and the PKA inhibitor H89 (0.1 µM) induced a negative inotropic effect which was associated with a decrease in Ca2+i. Since PKA increases Ca2+ release through sarcoplasmic reticulum RyR channels, CaSF was measured as an index of RyR open probability. The generation of CaSF was prevented by KH7. Finally, we investigated the potential role of sAC activation on NBC activity. NBC-mediated recovery from acidosis was faster in the presence of KH7 or H89, suggesting that the pathway sAC-PKA is negatively regulating NBC function, consistent with a negative feedback modulation of the HCO3- influx that activates sAC. In summary, the results demonstrated that the complex NBC-sAC-PKA plays a relevant role in Ca2+ handling and basal cardiac contractility.

Evolución infrecuente de sinoviosarcoma de muslo / Uncommon evolution after excision of a thigh synovial sarcoma

Background: Synovial sarcoma is a soft tissue tumor with a high degree of local and metastatic invasion. Case report: We report a 26 years old smoker woman with a history of a synovial tumor excised from the right thigh, who required a hip prosthesis for a pathological fracture due to metastases. Two years after, a lung metastasis in the left upper lobe was excised and treated with chemo and radiotherapy. Two years later a new lung nodule was found and excised. Pathology confirmed that they were metastases of the primary tumor. Three months after this last excision, the patient is asymptomatic.

Introducción: El sinoviosarcoma es una neoplasia de partes blandas con alto grado de invasión local y producción de metástasis. Caso clínico: Mujer de 26 años con 2 episodios secuenciales de metástasis pulmonar a lo largo de 6 años posterior al tratamiento del tumor primario. Patología de tratamiento muy complejo.