Histamine-induced hypotension modified by H1 and H2 antagonists in the monkey (Macaca mulatta).

Blocking H2 receptors with burimamide in the dose used (20 mg/kg) approximately doubles the amount of histamine needed to produce the same effect as seen when H1 antagonists (chlorpheniramine or mepyramine) are used alone. The Kz ratios for chlorpheniramine-chlorpheniramine plus burimamide are 117-204 and for mepyramine-mepyramine phus burimamide are 200-478. H1 and H2 receptors, in the monkey, when stimulated, both cause cardiovascular responses in the same direction.