MacLeod K M, Wenkstern D, McNeill J H
Eur J Pharmacol. 1986 May 27;124(3):331-6. doi: 10.1016/0014-2999(86)90235-9.
Dissociation constants and receptor reserves for histamine acting at H2 receptors in guinea-pig right atria and papillary muscles were measured using the irreversible H2 receptor antagonist L-643,441. Histamine alone was less potent in papillary muscles than in right atria, and maximum responses of papillary muscles to histamine were more susceptible to depression by L-643,441 than were maximum responses of right atria. However, dissociation constants (-log KA values) for histamine calculated using 3 different doses of L-643,441 were 0.5 log unit greater in papillary muscles than in right atria. A more marked difference was found in the estimates of receptor reserve for histamine, which appeared to be much greater in right atria than papillary muscles.
使用不可逆的H2受体拮抗剂L-643,441测定了组胺作用于豚鼠右心房和乳头肌中H2受体的解离常数和受体储备。单独使用组胺时，其在乳头肌中的效力低于右心房，且乳头肌对组胺的最大反应比右心房的最大反应更容易受到L-643,441的抑制。然而，使用3种不同剂量的L-643,441计算得出的组胺解离常数（-log KA值）在乳头肌中比在右心房中高0.5个对数单位。在组胺受体储备的估计值中发现了更显著的差异，右心房中的受体储备似乎比乳头肌中的大得多。
