Calcitonin gene-related peptide and its specific binding sites in the cardiovascular system of rat.
The concentration of calcitonin gene-related peptide in rat cardiovascular tissues was determined by a specific and sensitive radioimmunoassay and the distribution of its specific binding sites was assessed by radioligand binding studies. The binding of [125I]calcitonin gene-related peptide to cardiovascular membranes was rapid, saturable, reversible and specific. In atrial membranes a single binding site with high affinity (Kd 1.5 nM) and low capacity (120 fmol/mg protein) was detected. The highest concentrations of both calcitonin gene-related peptide and its binding sites were found in the peripheral and mesenteric arteries. The immunoreactive calcitonin gene-related peptide levels were lower in major vessels and lowest in the heart. The number of calcitonin gene-related peptide specific binding sites also showed a similar pattern with the exception of a high concentration of binding sites present in the atria. These findings, together with the proven vasodilatory activity of calcitonin gene-related peptide, suggest that this peptide has an important role as a modulator of peripheral vascular tone and perhaps a direct action of the heart.
Wimalawansa
S J
SJ
Department of Chemical Pathology, Royal Postgraduate Medical School, London, U.K.
MacIntyre
I
I
D000818:Animals; D001665:Binding Sites; D002116:Calcitonin / Q000235:genetics / Q000378:metabolism*; D015740:Calcitonin Gene-Related Peptide; D002319:Cardiovascular System / Q000378:metabolism*; D008297:Male; D008566:Membranes / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism*; D011863:Radioimmunoassay; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D018003:Receptors, Calcitonin; D011956:Receptors, Cell Surface / Q000378:metabolism; D014665:Vasodilator Agents / Q000378:metabolism
D009479:Neuropeptides; D018003:Receptors, Calcitonin; D011956:Receptors, Cell Surface; D014665:Vasodilator Agents; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide