Characterization of [3H]nifedipine binding sites in rabbit myocardium

Characterization of [3H]‐nitrendipine binding to uterine smooth muscle plasma membrane and its relevance to inhibition of calcium entry

“…A comparison of the density of the binding sites with the data reported by others is not justified since this parameter, which is usually expressed on the basis of protein concentration, will be dependent on the degree of enrichment of the membrane fractions. In the various published results (DePover et al, 1982;Bolger et el., 1982;Holck et al, 1982;Triggle et al, 1982;Williams & Tremble, 1982), both tissue homogenates and microsomal fractions have been used. Working with a preparation of rat myometrium which was highly enriched with plasma membrane, Grover et al (1984) recently presented data on [3H]-nitrendipine binding.…”

“…Dihydropyridines represent the most potent class of calcium entry blockers. Recently, high affinity binding to various tissues, including heart and smooth muscle, has been described for one of the most potent dihydropyridine calcium entry blockers, namely [3H]-nitrendipine (DePover et al, 1982;Bolger et al, 1982;Holck et al, 1982;Triggle et al, 1982;Williams & Tremble, 1982). In the present study, binding of this radioligand to isolated plasma membranes from uterine smooth muscle was used to characterize calcium channels in this tissue.…”

Inhibition of myocardial Ca2+ channels by three dihydropyridines with different structural features: potential‐dependent blockade by Ro 18–3981

“…Extensive investigations have documented the existence of high-affinity DHP binding sites in cardiac membranes (Bellemann et al, 1981;Holck et al, 1982; Triggle & Janis, 1984a). However, when comparing results of pharmacological and electrophysiological studies (Lee & Tsien, 1983; Janis & Triggle, 1984) with those from binding studies (Holck et al, 1982;1984), a large discrepancy (> 10 fold) is encountered in the concentrations of DHPs required to suppress myocardial ICa and to inhibit [3H1-nitrendipine binding. Recent investigations suggest that the Ca2" channel blocking potencies of DHPs such as nitrendipine (Bean, 1984;Reuter et al, 1985) or 'Author for correspondence. nisoldipine (Sanguinetti & Kass, 1984) Hof, 1985).…”

High and concentration‐proportional accumulation of [3H]‐nitrendipine by intact cardiac tissue

“…In the case of cardiac membranes the KD values of different dihydropyridines were found to lie in the nanomolar range (e.g. Holck et al, 1982;Janis et al, 1982). For nitrendipine, the KD was usually found to be 1-3 x 10-'M when determined in membrane preparations from cardiac tissues (Bellemann et al, 1981;Ehlert et al, 1982;Janis et al, 1982;Murphy & Snyder, 1982;Sarmiento et al, 1983;Chatelain et al, 1984;Gould et al, 1984;Schwartz & Velly, 1985).…”