Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

1. A 'P2' membrane fraction of bovine tracheal smooth muscle displays high affinity (KD 3.8 +/- 0.2 nM), saturable (Bmax 1003 +/- 170 fmol mg-1 protein) and reversible binding of D-myo[3H]-inositol 1,4,5-trisphosphate ([3H]-Ins(1,4,5)P3). 2. This binding site shows strict stereo- and positional specificity for the D-Ins(1,4,5)P3 isomer with L-Ins(1,4,5)P3, DL-Ins(1,3,4,5)P4 and D-Ins(1,3,4)P3 displacing [3H]-Ins(1,4,5)P3 with Ki values of 20 microM, 0.35 microM and 2.4 microM, respectively. 3. Specific binding of [3H]-Ins(1,4,5)P3 is enhanced at alkaline pH values (maximal at pH 7.75) and, in distinct contrast to [3H]-Ins(1,4,5)P3 binding in rat cerebellum membranes, is not inhibited by Ca2+ (5-500 microM). 4. Heparin displaces [3H]-Ins(1,4,5)P3 specific binding with an IC50 of 7.6 +/- 1.0 micrograms ml-1. 5. Comparative studies demonstrated specific [3H]-Ins(1,4,5)P3 binding in bovine cardiac atrial preparations (Bmax 75 +/- 5 fmol mg-1 protein) and very low specific [3H]-Ins(1,4,5)P3 binding in bovine cardiac ventricle and skeletal muscle membranes (less than or equal to 25 fmol mg-1 protein).

Type

Journal article

Journal

Br J Pharmacol

Publication Date

02/1990

Volume

99

Pages

297 - 302

Keywords

Animals, Binding Sites, Calcium, Calcium Channels, Cattle, Cerebellum, Hydrogen-Ion Concentration, In Vitro Techniques, Inositol 1,4,5-Trisphosphate, Inositol 1,4,5-Trisphosphate Receptors, Kinetics, Male, Membranes, Muscle, Smooth, Rats, Rats, Inbred Strains, Receptors, Cell Surface, Receptors, Cytoplasmic and Nuclear, Stereoisomerism, Trachea