Open AccessEffect of Concomitant β‐Adrenoceptor Stimulation on α 1 ‐Adrenoceptor‐Mediated Increase of Inositol‐1, 4, 5‐trisphosphate Mass in Adult Rat Cardiomyocytes
Author(s) -
Viko Håvard,
Sandnes Dagny,
Skomedal Tor,
Osnes JanBjørn
Publication year - 1998
Publication title -
pharmacology & toxicology
Language(s) - English
Resource type - Journals
eISSN - 1600-0773
pISSN - 0901-9928
DOI - 10.1111/j.1600-0773.1998.tb01437.x
Subject(s) - stimulation , endocrinology , medicine , inositol , inositol phosphate , basal (medicine) , alpha (finance) , adrenergic receptor , inositol trisphosphate , radioligand , receptor , chemistry , biology , insulin , construct validity , nursing , patient satisfaction
The aim of the present study was to investigate the accumulation of inositol‐1, 4, 5‐trisphosphate (IP 3 ) in isolated adult rat ventricular cardiomyocytes after α 1 and β‐adrenoceptor stimulation, separate and in combination, in order to elucidate a possible influence of concomitant β‐adrenoceptor stimulation on the α 1 ‐adrenoceptor stimulated response. IP 3 was measured by a radioligand binding assay based on an (1, 4, 5)IP 3 ‐specific binding protein from bovine adrenal cortex. The basal IP 3 content was 4.06 + 0.31 pmol/mg protein (N=56). α 1 ‐Adrenoceptor stimulation resulted in a rapid increase in the IP 3 level, which reached a plateau, 50–80% above basal level, at 10–30 sec. The plateau lasted at least up to 120 sec, while at 300 sec. there was no significant difference between control values and values after α 1 ‐adrenoceptor stimulation. Li + did not affect either the basal IP 3 level, or the magnitude or time course of α 1 ‐adrenoceptor‐stimulated IP 3 accumulation. Combined adrenoceptor stimulation gave a similar response as separate α 1 ‐adrenoceptor stimulation, whereas there was no significant change in the IP 3 level after β‐adrenoceptor stimulation. No inhibitory influence of simultaneous β‐adrenoceptor stimulation on the α 1 ‐adrenoceptor‐stimulated increase of IP 3 mass was revealed.