Donor heart preservation with the potassium channel opener pinacidil: comparison with University of Wisconsin and St. Thomas' solution

BACKGROUND

Hyperpolarized arrest with the potassium channel opener pinacidil has been shown to provide effective myocardial protection during short-term global ischemia. This study tested the hypothesis that pinacidil may provide effective long-term protection for heart transplant preservation.

METHODS

Four concentrations of pinacidil (50 microM, 100 microM, 0.5 mM, 1.0 mM) mixed in Krebs-Henseleit solution were compared with University of Wisconsin and St. Thomas' Hospital solutions in a Krebs-Henseleit perfused rabbit Langendorff model (n = 6 for each group). Hearts underwent 4 hours of hypothermic (4 degrees C) storage. Over a wide range of volumes, left ventricular systolic function, diastolic compliance, and coronary flow were measured prior to and following storage. Time to mechanical and electrical arrest, and post-ischemic percent tissue water were also measured.

RESULTS

Pinacidil 0.5 mM provided the best preservation of post-ischemic systolic function and coronary flow compared with the other pinacidil concentrations and was statistically equivalent to St. Thomas' solution in terms of post-ischemic systolic, diastolic, and flow properties. However, hearts protected with University of Wisconsin solution had significantly better preservation of systolic function and coronary flow.

CONCLUSIONS

This investigation demonstrated that pinacidil in Krebs-Henseleit solution possesses efficacy in long-term donor heart preservation. Pinacidil was equivalent to St. Thomas' solution but inferior to University of Wisconsin solution. Hyperpolarized arrest with potassium channel openers may be a novel strategy to improve donor heart preservation.

Preconditioning with cromakalim improves long-term myocardial preservation for heart transplantation

BACKGROUND

Myocardial preservation for heart transplantation relies on hyperkalemic cardiac arrest and hypothermic storage. Our study investigated whether pretreatment with a potassium-channel opener (cromakalim) before prolonged storage in an extracellular fluid improves left ventricular recovery.

METHODS

Rabbit hearts were submitted to 6-hours' cold storage and assessed on a blood-perfused isolated heart preparation. Hemodynamic recovery, enzyme release (creatine kinase and lactate dehydrogenase), and adenine nucleotide content were determined. Five groups were tested: control (n=6), no ischemia; UW group (n=7), hearts arrested with and stored in University of Wisconsin solution; STH group (n=5), hearts arrested with and stored in St. Thomas' Hospital solution; cromakalim group (n=6), hearts pretreated with cromakalim (30 microg/kg) before arrest with and storage in St. Thomas' Hospital solution; and glibenclamide group (n=5), hearts pretreated with cromakalim followed by glibenclamide (a potassium-channel blocker) before arrest with and storage in St. Thomas' Hospital solution.

RESULTS

Hemodynamic recovery was improved and enzyme release was lower in the UW group than in the STH group. Compared with the STH group, the group pretreated with cromakalim had significantly decreased left ventricular end-diastolic pressures, increased left ventricular developed pressures, increased maximal values of positive and negative rates of rise of left ventricular pressure, and increased time constant of isovolumetric relaxation. Hemodynamic recovery was similar in the UW group and cromakalim groups. Glibenclamide did not abolish the effects of cromakalim. None of the protocols affected myocardial energy stores.

CONCLUSION

Pretreatment with cromakalim affords additional protection to that provided by cardioplegic arrest and prolonged cold storage using an extracellular solution. The intracellular mechanisms involved remain to be determined.