Characteristics of endothelin binding sites in the spinal cord of spontaneously hypertensive rats.
The binding of [125I]sarafotoxin 6b (SRT 6b) and [125I]endothelin-1 (ET-1) to endothelin (ET) receptors of neuronal membranes prepared from cerebral cortex and spinal cord of 8-week-old spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) was determined. SHR had significantly higher blood pressure as compared to WKY. Heart rate was similar in SHR and WKY. [125I]SRT 6b and [125I] ET-1 bound to the membranes of cerebral cortex and spinal cord at a single, high affinity site. The binding of [125I]SRT 6b and [125I]ET-1 in the cerebral cortex and spinal cord membranes was found to be similar in SHR and WKY. Concentration-dependent inhibition of [125I]ET-1 binding in spinal cord membranes by unlabeled ET-1, ET-2 and ET-3 was performed. The Ki values were found to be 2.35 +/- 0.68, 0.29 +/- 0.08 and 24.10 +/- 5.90 nM for ET-1, ET-2 and ET-3, respectively in WKY. The Ki values of ET-1 and ET-2 were found to be similar in WKY and SHR. However, the Ki value of ET-3 were found to be significantly lower (P less than 0.004) in SHR as compared to WKY. Concentration-dependent inhibition of [125I]SRT 6b binding in spinal cord membranes by unlabeled ET-1, ET-2 and ET-3 were also performed. The Ki values were found to be 9.50 +/- 2.10 pM, 0.17 +/- 0.04 nM and 31.20 +/- 6.00 nM for ET-1, ET-2 and ET-3, respectively in WKY. The Ki values of ET-1 and ET-2 were found to be similar in WKY and SHR.(ABSTRACT TRUNCATED AT 250 WORDS)
Gulati
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Department of Pharmacodynamics (m/c 865), University of Illinois, Chicago 60612.
D000818:Animals; D001667:Binding, Competitive; D001794:Blood Pressure; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D016232:Endothelins / Q000378:metabolism*; D006339:Heart Rate; D007700:Kinetics; D009474:Neurons / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017466:Receptors, Endothelin; D013116:Spinal Cord / Q000378:metabolism*; D014662:Vasoconstrictor Agents / Q000378:metabolism; D014757:Viper Venoms / Q000378:metabolism
D016232:Endothelins; D011956:Receptors, Cell Surface; D017466:Receptors, Endothelin; D014662:Vasoconstrictor Agents; D014757:Viper Venoms; C057354:sarafotoxins s6