PRKG1 and chronic obstructive pulmonary disease: One thesis is that hypertension along with the other factors such as obesity, DM, CKD and COPD (chronic obstructive pulmonary disease), induce a pro-inflammatory state resulting in coronary microvascular endothelial dysfunction, reduced bioavailability of nitric oxide, reduced cyclic guanosine monophosphate, and reduced protein kinase G (PKG) activity in the cardiomyocytes, that leads to increased LV stiffness (Paulus and Tschöpe, 2013[84]; Lee and Park, 2021[62]).