Figure 1. Fetal cardiovascular responses to acute hypoxaemia.
Values are means ±s.e.m. of every minute for cardiovascular variables during the experimental protocol when the fetuses were infused with saline (n = 6), V1 antagonist (n = 6), or phentolamine (n = 6). The boxes represents the episode of acute hypoxaemia. Saline or antagonist infusion was started 15 min prior to hypoxaemia and ran continuously until the end of the hypoxaemic challenge (bar). All 6 fetuses died during hypoxaemia when treated with phentolamine. Because the time course of fetal cardiovascular collapse in hypoxaemia during phentolamine treatment was different from fetus to fetus, the last data point shown for all cardiovascular variables in phentolamine-treated fetuses represents the mean ±s.e.m. when all 6 fetuses were still alive.