title: Gene deletion of P2Y4 receptor lowers exercise capacity and reduces myocardial hypertrophy with swimming exercise.
abstract: Nucleotides released within the heart under pathological conditions can be involved in cardioprotection or cardiac fibrosis through the activation purinergic P2Y(2) and P2Y(6) receptors, respectively. We previously demonstrated that adult P2Y(4)-null mice display a microcardia phenotype related to a cardiac angiogenic defect. To evaluate the functional consequences of this defect, we performed here a combination of cardiac monitoring and exercise tests. We investigated the exercise capacity of P2Y(4) wild-type and P2Y(4)-null mice in forced swimming and running tests. Analysis of their stress, locomotion, and resignation was realized in open field, black and white box, and tail suspension experiments. Exercise-induced cardiac hypertrophy was evaluated after repeated and prolonged exercise in P2Y(4) wild-type and P2Y(4)-null hearts. We showed that P2Y(4)-null mice have a lower exercise capacity in both swimming and treadmill tests. This was not related to decreased motivation or increased stress, since open field, white and black box, and mouse tail suspension tests gave comparable results in P2Y(4) wild-type and P2Y(4)-null mice. Heart rate and blood pressure rose normally in P2Y(4)-null swimming mice equipped with a telemetric implant. On the contrary, we observed a delayed recovery of postexercise blood pressure after exercise in P2Y(4)-null mice. The heart rate increment in response to catecholamines was also similar in P2Y(4) wild-type and P2Y(4)-null implanted mice, which is consistent with a similar level of cardiac β-receptor expression. Interestingly, the heart of P2Y(4)-null mice displayed a reduced sympathetic innervation associated with a decreased norepinephrine level. We also demonstrated that exercise-induced cardiac hypertrophy was lower in P2Y(4)-null mice after repeated and prolonged exercise. This was associated with a lower increase in cardiomyocyte size and microvessel density. In conclusion, besides its role in cardiac development, P2Y(4) receptor could constitute an important regulator of acute and chronic response to exercise.
authors.affiliation: Institute of Interdisciplinary Research, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Michael
authors.initials: M
authors.lastname: Horckmans
authors.forename: Elvira
authors.initials: E
authors.lastname: Léon-Gómez
authors.forename: Bernard
authors.initials: B
authors.lastname: Robaye
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Balligand
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Boeynaems
authors.forename: Chantal
authors.initials: C
authors.lastname: Dessy
authors.forename: Didier
authors.initials: D
authors.lastname: Communi
mesh_terms: D000320:Adrenergic Fibers / Q000378:metabolism; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal; D001794:Blood Pressure / Q000235:genetics; D018660:Blood Pressure Monitoring, Ambulatory; D006332:Cardiomegaly / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D059267:Cardiomegaly, Exercise-Induced / Q000235:genetics*; D002395:Catecholamines / Q000378:metabolism; D004195:Disease Models, Animal; D004280:Dobutamine / Q000494:pharmacology; D005080:Exercise Test; D017079:Exercise Tolerance / Q000187:drug effects / Q000235:genetics*; D017353:Gene Deletion; D005838:Genotype; D006321:Heart / Q000294:innervation / Q000503:physiopathology*; D006339:Heart Rate / Q000235:genetics; D007035:Hypothermia / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D008124:Locomotion; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010641:Phenotype; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000172:deficiency* / Q000235:genetics; D020127:Recovery of Function; D013550:Swimming; D013686:Telemetry; D013997:Time Factors
chemical_list: D000318:Adrenergic beta-Agonists; D002395:Catecholamines; D011943:Receptors, Adrenergic, beta; D018048:Receptors, Purinergic P2; C104749:purinoceptor P2Y4; D004280:Dobutamine