Caveolae are flask-shaped invaginations of the membrane (50-100 nm in diameter) found in almost every cell of the body. They are a specialised form of lipid raft with a layer of integral caveolin proteins, covered on the intracellular surface with a filamentous network of cavin proteins. Together this is known as the caveolar coat complex (CCC) [1]. In the cardiac myocyte, caveolae have been shown to contribute to mechanoprotection and the regulation of numerous signalling pathways [2]. However, little is known about the composition and structure of caveolae in these cells. Current knowledge is largely based on experimental evidence from cell lines which express caveolin 1/2 and cavin 1/2/3, but which lack the muscle-specific caveolar proteins (caveolin 3 and cavin 4). Here we examine the organisation of caveolar proteins in the cardiac myocyte using in situ crosslinking of caveolin and cavin, alongside a new form of super-resolution microscopy. Ventricular myocytes were isolated by Langendorff-perfusion of adult rat hearts with a collagenase/protease-containing solution. HeLa cells and cardiac myocytes were incubated with the cross-linker dithiobis(succinimidyl propionate) (DSP) for isolation of the CCC on a sucrose velocity gradient [1]. Myocytes attached to coverslips were dual labelled with caveolin 3 and cavin 1/4. 10X expansion microscopy (10XEX) was performed to achieve ~25nm resolution with Airyscan imaging [3]. As described by others [1], the CCC isolated from HeLa cells was ~80S in size and contained the main ubiquitous caveolar protein isoforms (caveolin 1 and cavin 1). In myocytes, the ~80S complex contained only caveolin 1 and cavin 1/4. Despite being expressed at 5 times the level of caveolin 1, caveolin 3 was absent from these complexes. Indeed, caveolin 3 migration in the sucrose gradient did not change with DSP. However, using 10XEX, caveolin 3 and cavin 1/4 can clearly be resolved within a single caveola with high levels of co-localisation. Together these data suggest a form of CCC in myocytes which contains both caveolin 3 and cavin 1/4, but with a different integration of caveolin 3 compared with caveolin 1.