NPPA and prediabetes syndrome: To delineate the specific role of ANP/GCA signaling in skeletal muscle in the pathogenesis of prediabetes, we developed a muscle-specific GCA knockdown mouse model (MKD-Gca) with the use of systemic adeno-associated virus 9 (AAV9)–tMCK-iCre in Gca fl/fl mice (Fig. 7A).