Activation of renal pelvic chemoreceptors in rats: role of calcitonin gene-related peptide receptors.
Substance P and calcitonin gene-related peptide (CGRP) increase afferent renal nerve activity (ARNA). A substance P receptor antagonist but not a CGRP receptor antagonist, h-CGRP (8-37), blocks the ARNA response to renal mechanoreceptor (MR) stimulation. We have examined whether calcitonin gene-related peptide activates renal pelvic sensory receptors and whether such activation contributes to renal chemoreceptor stimulation. The calcitonin gene-related peptide receptor antagonist, h-CGRP (8-37) [0.01-10 micromol L-1] dose-dependently decreased (29 +/- 4-86 +/- 13%, P < 0.01) the ipsilateral afferent renal nerve activity in response to the renal pelvic administration of calcitonin gene-related peptide (0.26 micromol L-1). Renal pelvic perfusion with 900 mM NaCl also increased ipsilateral ARNA (23 +/- 3% increase, P < 0.02) and contralateral urinary sodium excretion (13 +/- 4% increase, P < 0. 05). However, these responses to hypertonic NaCl were unaltered by h-CGRP (8-37). Renal pelvic perfusion with 1 or 10 microM h-CGRP (8-37) also failed to alter the ARNA responses to KCl (31.25, 62.5 and 125 mM). These results indicate that there are sensory receptors in the renal pelvic area that are responsive to calcitonin gene-related peptide. The activation of these receptors elicits a contralateral natriuretic response. In contrast, the activation of renal calcitonin gene-related peptide receptors does not contribute to renal chemoreceptor activation.
Gontijo
J A
JA
Disciplina de Medicina Interna, Laboratório de Metabolismo Hidro-Salino, Núcleo de Medicina e Cirurgia Experimental, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil.
Kopp
U C
UC
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D002628:Chemoreceptor Cells / Q000378:metabolism*; D007682:Kidney Pelvis / Q000187:drug effects / Q000294:innervation*; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D010446:Peptide Fragments / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology
D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D010446:Peptide Fragments; D018015:Receptors, Calcitonin Gene-Related Peptide; C058636:calcitonin gene-related peptide (8-37); D012965:Sodium Chloride; D011189:Potassium Chloride; D015740:Calcitonin Gene-Related Peptide