Mice with a cardiac ovexpression of the human beta3-adrenergic receptor were produced by microinjection of a construct with A or C isoform gene under the control of the alpha myosin heavy chain promoter. Phenotypic analyses comprised beta3-AR mRNA and protein determinations, histological studies, electrocardiogram, contractility and cyclic nucleotide measurements.Transgenic mice that ovexepressed the A form were cryopreserved while transgenic mice that ovexepressed the C form are already alive.