Table 1.

Factors that maintain ductal patency in utero.

Low oxygen tension

High levels of circulating prostaglandins

Increase in nitric oxide production

Increase in carbon monoxide production

High levels of circulating adenosine

Increase in intracellular cAMP and cGMP

Raised plasma concentrations of atrial natriuretic peptide

Activation of potassium channels Kv1.5, Kv1.2, Kv2.1, KATP, BKca