Blood-brain barrier function following drug-induced hypotension in the dog

To examine the effects of hypotension induced either with trimethaphan (TMP) or nitropusside (NTP) on blood-brain barrier (BBB), leakage of Evans blue was observed in dogs. Dogs given TMP were divided into two groups. In TMP-group 1, seven dogs were rendered hypotensive to mean cerebral perfusion pressure of 45 mmHg for 45 min and then of 30 mmHg for 45 min. In TMP-group 2, three dogs were examined neurologically 3 days after arterial hypotension, identical to that in the TMP-group 1. Dogs given NTP were divided into four groups. In NTP-group 1 (at dose ＜ 1mg/kg) and NTP-group 4 (＞1mg/kg), seven dogs each rendered hypotensive, indentical to the TMP-group 1. IN NTP-group 2, three dogs were examined as the TMP-group 2. In NTP-group 3, seven dogs rendered hypotensive to mean cerebral perfusion pressure 45 mmHg for 45 min. In all dogs, the dorsal cortical surface and serial coronal sections were examined for evidence of Evans blue leakage. The mean Evans blue leakage score (±SEM) for TMP-group 1 and 2 was 12±6, 0±0, respectively, and for NTP-groups 1, 2, 3 and 4 was 105±14, 30±7, 6±6, 125±26, respectively. These results suggest that dysfunction of BBB in the NTP-groups was more pronounced than in the TMP-groups.