Cardiorenal effects of behavioral inhibition of breathing

This article reviews evidence that mild, but sustained, inhibition of breathing can affect blood pressure regulation via effects of increased PCO2 on sodium regulation. Experiments with micropigs are summarized which show that anticipation of the onset of a familiar avoidance task is accompanied by sustained increases in PCO2, increases in plasma hydrogen and bicarbonate ion concentrations, decreases in hematocrit, and increases in circulating levels of sodium pump inhibitors that are sensitive to plasma volume. Observational studies with humans using an ambulatory respiration monitor characterize episodes of inhibited breathing occurring in the natural environment. Experimental studies with human subjects show that voluntary maintenance of end-tidal CO2 near the upper end of the normal range results in decreases in renal sodium excretion, increases in plasma sodium pump inhibitors and inhibition of sodium pump activity. Together, these studies are consistent with the view that behavioral stress can influence blood pressure regulation via sustained inhibition of respiration which acidifies the plasma and increases sodium/hydrogen exchange in kidneys and blood vessels.