In fact, MetS rats responded to βAR activation with positive chronotropic, inotropic, and lusitropic responses during the first seconds of activation, as indicated by the increase in heart rate, CO, EF, end-systolic pressure, LVDP, and +dP/dt, and reduced −dP/dt as well as τ after isoproterenol administration, despite cardiac performance being compromised in resting conditions. This evidence concerns the gene ADRB2 and metabolic syndrome.