Inverse relationship between the circulating plasma autotaxin activity and blood pressure in normal pregnant rats.

Autotaxin (ATX) is a secreted lysophospholipase D that generates lysophosphatidic acid (LPA). We investigated circulating ATX activity and blood pressure (BP) in rats throughout pregnancy. Systolic BP gradually decreased after gestational day 15, reached a nadir on day 21, and rebounded on day 1 postpartum. Conversely, plasma ATX activity rose from day 12 through days 19-21 and declined thereafter. A bolus intravenous LPA injection on day 21 significantly increased BP. Although a single anti-ATX serum injection on day 21 showed little acute effect, continuous administration via osmotic mini-pump from day 18 significantly delayed the late-gestational BP drop. These results demonstrate a novel inverse relationship between circulating ATX activity and BP in late-pregnant rats.