IN VIVO SUPPLEMENTATION OF CREATINE AND RIBOSE PRESERVES HYPOXIC HEARTS FROM APOPTOSIS AND RIGHT VENTRICLE HYPERTROPHY.

It was previously found that H9c2 cardiomyocytes exposed to 24-h ischemia (1% O2 with glucose deprivation), were rescued by administration of 2.5 mM creatine + 5 mM D-ribose, while creatine or D-ribose alone were ineffective (1). These findings correlated with up-regulation of protein kinase B (Akt) phosphorylation. Creatine+D-ribose also blunted adenosine monophosphate-activated protein kinase (AMPK) and down-regulated apoptosis by reducing caspase-3 activation and poly (ADP-ribose) polymerase cleavage. In order to test the existence of an analogous mechanism in an in vivo context, five week-old mice were exposed to an atmosphere containing 10% O2 for 10 days, sacrificed and myocardial and pulmonary tissue harvested for structural and biochemical analyses. Mice were gavaged daily with vehicle, creatine, D-ribose or both. Results showed that hypoxia induced marked right ventricle hypertrophy and left ventricle apoptosis. Both phenotypes were slightly reduced by the administration of either creatine or D-ribose, whereas the simultaneous administration almost completely reverted the effects of hypoxia. Furthermore, creatine+D-ribose contributed to blunt the increases in the activity of AMPK, Akt and JNK, but not of ERK, caused by hypoxia. The increase in AMPK during hypoxia is an expected finding secondary to inadequate O2 supply with respect to needs. AMPK is probably upstream of Akt activation; in turn, Akt exerts pro-survival activities, however, by modulating the PI3-kinase pathway, Akt regulates cardiomyocyte size, thus inducing physiological cardiac hypertrophy (2). In addition, the development of right ventricle hypertrophy was found to be associated to left ventricle apoptosis (3), as reported here. During hypoxia, pulmonary hypertension, causing pressure overload, contributes to right ventricle hypertrophy. We show here that the mRNA expression of endothelin-1, a short-lived peptide responsible for the pulmonary and heart disease (4), is increased by hypoxia. The administration of creatine+D-ribose led to reduction of the hypoxia-induced pulmonary overexpression of endothelin-1 mRNA. Whereas creatine improves bioenergetics by recycling ADP into ATP via its shuttle property (5), ribose protects ischemic hearts by replenishing building blocks for ATP synthesis (6). By re-energization of not irreversibly-damaged myocardial cells. creatine+ribose appear to counteract myocardial injury by blunting the pathways originated from AMPK and Akt activation. This may constitute a useful therapeutic approach in several human diseases that involve systemic hypoxia, as for example chronic pulmonary obstructive diseases, heart failure as well as various forms of anemia. References: 1- Caretti A et al, Cell Physiol Biochem.(2010), 26:831-838. 2- Rigor DL et al, Am J Physiol Heart Circ Physiol. (2009);296:H566-72. 3- Kitahori K et al, Circ Heart Fail. (2009);2:599-607. 4- Karmouty-Quintana H et al, FASEB J. (2012); 26:2546-2557. 5- Kammermeier H. J Mol Cell Cardiol. (1987);19:115-118. 6- Smolenski RT et al,. J Mol Cell Cardiol. (1998);30:673-683.