Adult female wild-type (WT) and NOS3−/− mice were anesthetized, intubated, and instrumented with left-ventricular pressure-volume catheters. Cardiac arrest was induced with intravenous potassium chloride. CPR was performed after 8 min of untreated arrest. ROSC rate, cardiac function, whole-blood nitrosylhemoglobin (HbNO) concentrations, heart NOS3 content and phosphorylation (p-NOS3), cyclic guanosine monophosphate (cGMP), and phospho-troponin I (p-TnI) were measured.
Despite equal quality CPR, NOS3−/− mice displayed lower rates of ROSC compared to WT (47.6 % [10/21] vs. 82.4 % [14/17], p < 0.005). Among ROSC animals, NOS3−/− vs. WT mice exhibited increased left-ventricular dysfunction and 120 min mortality. Prior to ROSC, myocardial effectors of NO signaling including cGMP and p-TnI were decreased in NOS3−/− vs. WT mice (p < 0.05). Following ROSC in WT mice, significant NOS3-dependent increases in circulating HbNO were seen by 120 min. Significant increases in cardiac p-NOS3 occurred between end-arrest and 15 min post-ROSC, while total NOS3 content was increased by 120 min post-ROSC (p < 0.05).
Genetic deletion of NOS3 decreases ROSC rate and worsens post-ROSC left-ventricular function. Poor cardiovascular outcomes are associated with differences in NOS3-dependent myocardial cGMP signaling and circulating NO metabolites.