Article date: May 1993
By: Kazuto Yazawa, Yasushi Abiko, in Volume 109, Issue 1, pages 142-147
Histamine receptor‐mediated modulation of the delayed outward potassium current (IK) was investigated in guinea‐pig single ventricular cells by the whole‐cell voltage clamp.
Histamine increased IK in a dose‐ dependent manner with a half‐maximum dose of 3.8 × 10−8 M. Histamine (10−6m) increased IK by a factor of 3.02 without a significant change in the current kinetics. The threshold dose of histamine for increasing IK was 10−9m and this value was similar to that for calcium current.
Cimetidine decreased IK in the presence of histamine, by shifting the dose‐response curve to histamine to the right. The pA2 value of cimetidine against histamine was 6.38.
Forskolin did not increase IK after application of 10−6m histamine, and histamine scarcely increased IK in the presence of a heat‐stable inhibitor of cyclic AMP‐dependent protein kinase (PKI).
We conclude that stimulation by histamine of IK is mainly by way of the H2‐receptor, and is mediated by cyclic AMP‐dependent phosphorylation.
Histamine receptor‐mediated modulation of the delayed outward potassium current (IK) was investigated in guinea‐pig single ventricular cells by the whole‐cell voltage clamp.
Histamine increased IK in a dose‐ dependent manner with a half‐maximum dose of 3.8 × 10−8 M. Histamine (10−6m) increased IK by a factor of 3.02 without a significant change in the current kinetics. The threshold dose of histamine for increasing IK was 10−9m and this value was similar to that for calcium current.
Cimetidine decreased IK in the presence of histamine, by shifting the dose‐response curve to histamine to the right. The pA2 value of cimetidine against histamine was 6.38.
Forskolin did not increase IK after application of 10−6m histamine, and histamine scarcely increased IK in the presence of a heat‐stable inhibitor of cyclic AMP‐dependent protein kinase (PKI).
We conclude that stimulation by histamine of IK is mainly by way of the H2‐receptor, and is mediated by cyclic AMP‐dependent phosphorylation.
DOI: 10.1111/j.1476-5381.1993.tb13544.x
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