Table 4

Species variation in H1-receptor antagonist potency (Ki, nM)

AntagonistGuinea pigHumanRatBovine
h14-a (CHO)H14-b(brain)h1 (CHO)H1(brain)h1 (C6)H1(brain)h1 (COS-7)H1 (Adrenal Medulla)
Mepyramine0.70.81.1,  (1.0)4-c
(+)-Chlorpheniramine0.90.83.5,  (4.4)4-c
(−)-Chlorpheniramine103200316350540  (>620)4-c 500760350
  • Unless otherwise stated, values show Kideterminations from inhibition of [3H]mepyramine binding. n.d., not determined.

  • 4-a h1 = transfected H1-receptor cDNA.

  • 4-b H1 = native/endogenous H1-receptor.

  • 4-c Values in parentheses show the values obtained from functional studies of the endogenous H1-receptor present in rat C6 cells (Peakman & Hill, 1994).