Hypertonic media produce Ca(2+)-dependent release of calcitonin gene-related peptide from capsaicin-sensitive nerve fibres in the rat urinary bladder.
Superfusion of slices of the rat urinary bladder with hypertonic NaCl produced a remarkable and concentration-dependent (150-280 mM) increase in the outflow of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI). This effect was completely abolished by pre-exposure of the tissue to capsaicin (10 microM for 20 min) or by superfusion with a Ca(2+)-free medium. Capsaicin (10 microM) was still able to release a consistent amount of CGRP-LI from tissue pre-exposed (20 min) to 280 mM NaCl. Similarly, hypertonic sucrose (160 mM added to the physiological salt solution) induced a consistent release of CGRP-LI that was abolished by capsaicin-pretreatment or in a Ca(2+)-free medium. The experiments demonstrate that hypertonic solutions activate the efferent function of capsaicin-sensitive neurons and suggest that this event may have some relevance in pathophysiological conditions of the lower urinary tract in which hypertonic urine may diffuse to submucosal layers.
Tramontana
M
M
Institute of Internal Medicine IV, University of Florence, Italy.
Cecconi
R
R
Del Bianco
E
E
Santicioli
P
P
Maggi
C A
CA
Alessandri
M
M
Geppetti
P
P
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002118:Calcium / Q000502:physiology*; D002211:Capsaicin / Q000494:pharmacology*; D006982:Hypertonic Solutions / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009994:Osmolar Concentration; D051381:Rats; D011919:Rats, Inbred Strains; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D013268:Stimulation, Chemical; D013395:Sucrose / Q000494:pharmacology; D001743:Urinary Bladder / Q000187:drug effects / Q000294:innervation*
D006982:Hypertonic Solutions; D012462:Saline Solution, Hypertonic; D013395:Sucrose; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin; D002118:Calcium