Long‐chain polyunsaturated fatty acids influence both β‐ and α‐adrenergic function of rat cardiomyocytes

Dietary polyunsaturated fatty acids (PUFA) have been reported to lower the incidence of cardiovascular diseases, but neither the mechanisms that determine these protective effects nor the specific influence of n‐3 vs. n‐6 PUFA series has been well established. The purpose of this work was to demonstrate the influence of the membrane long‐chain fatty acid composition on the spontaneous contractile activity and the adrenergic function of rat cardiomyocytes in culture. Cells were grown for 24 h in a standard culture medium and then for 4 d in media that contained either n‐3 (eicosapentaenoic acid and docosahexaenoic acid) or n‐6 (arachidonic acid) PUFA. The n‐6/n‐3 ratio was 1.2 in n‐3 cells compared with 20.1 in n‐6 cells. The basal contractile properties of these cardiomyocytes were not affected by the PUFA phospholipid composition. However, these modifications influenced the adrenoceptor function because the β‐adrenergic stimulation by isoproterenol (10−7 M) induced a positive chronotropic response that was significantly greater in n‐3 cells. Moreover, the chronotropic response to α‐adrenoceptor stimulation by phenylephrine (10−6 M) appeared significantly more pronounced in the n‐3 cells than in the n‐6 cells. However, the parameters related to the inotropic response induced by these agonists did not differ significantly between the two groups of cells. These results suggested that the membrane long‐chain PUFA composition does not influence the basal cardiac contractility and automaticity but is able to modulate the chronotropic function of both α‐ and β‐adrenoceptors.