Cyclosporine A downregulates intragraft platelet-derived growth factor-α mRNA expression after clinical heart transplantation

Cardiac surgery in renal transplant recipients: experience from Washington Hospital Center

BACKGROUND

The number of renal transplant survivors requiring surgical treatment for cardiovascular diseases is increasing. A retrospective study was conducted to determine the outcomes of renal transplant recipients undergoing cardiac surgery.

METHODS

Fifty-seven renal transplant recipients whose cardiac surgery was performed between 1987 and 2004, and whose allograft was functioning at the time of cardiac surgery, were identified. We analyzed postoperative mortality and morbidity as well as late mortality.

RESULTS

Among 57 patients, 70.2% had hypertension, 54.4% diabetes, and 28.1% poor left ventricular function (ejection fraction < 0.35). Preoperative renal insufficiency (serum creatinine level > or = 3 mg/dL) was noted in 12.3% of the patients. Coronary artery disease was the dominant indication for the surgery. The median interval from renal transplant to cardiac surgery was 60 months. In-hospital mortality was 5.3%. All deaths were cardiac-related. Infectious complications occurred in 17.5% of the patients. Acute allograft failure requiring hemodialysis occurred in 28.6% of the patients with preoperative renal insufficiency, more frequent than those without preoperative renal insufficiency. Multivariable analysis identified preoperative renal insufficiency, mitral valve disease, and left ventricular dysfunction as independent predictors of in-hospital major adverse events (including death, infection, and renal failure). The 3-year survival was 71% after a median follow-up of 34 months.

CONCLUSIONS

Infection control and renal protection should be stressed to ensure the safety of cardiac surgery in this patient group, while preoperative renal insufficiency, mitral valve disease, and left ventricular dysfunction are associated with early adverse outcomes. In the renal transplant recipients undergoing an isolated CABG, avoidance of cardiopulmonary bypass and use of arterial grafts might lead to better outcomes.

Functional coupling of calcineurin and protein kinase A in mouse ventricular myocytes

We examined the role of the Ca(2+)-regulated protein phosphatase calcineurin in controlling Ca(2+) signalling in mouse ventricular myocytes. Membrane currents and voltage were measured in single myocytes using the patch-clamp technique. Cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) was measured in cells loaded with the fluorescent Ca(2+) indicators fluo-4 or fura-2 using a confocal or epifluorescence microscope. Inhibition of calcineurin with cyclosporin A (CsA, 100 nM) or the calcineurin auto-inhibitory peptide (CiP, 100 microM), increased the amplitude and rate of decay of the evoked [Ca(2+)](i) transient and also prolonged the action potential (AP) of ventricular myocytes to a similar extent. The effects of CsA (100 nM) and 100 microM CiP on the [Ca(2+)](i) transient and AP were not additive. Calcineurin inhibition did not modify the K(+) currents responsible for repolarisation of the mouse ventricle. Instead, inhibition of calcineurin increased the amplitude of the Ca(2+) current (I(Ca)) and the evoked calcium transient normalized to the I(Ca). Calcium sparks, which underlie the [Ca(2+)](i) transient, had a higher frequency and amplitude, suggesting an elevation of SR calcium load. Inhibition of protein kinase A (PKA) prevented the effects of calcineurin inhibition, indicating that calcineurin opposes the actions of PKA. Finally, immunofluorescence images suggest that calcineurin and PKA co-localize near the T-tubules of ventricular myocytes. We propose that calcineurin and PKA are co-localized to control Ca(2+) influx through calcium channels and calcium release through ryanodine receptors.