Somatostatin inhibition of fictive respiration is modulated by pH.
We studied the respiratory effects of the tetradecapeptide somatostatin (SST) upon fictive respiration using the in vitro brain stem spinal cord preparation from new-born mouse. We found that SST inhibits respiration, an effect that was potentiated when the chemical drive to respiration was increased. SST inhibited fictive respiration decreasing both the frequency and amplitude in a dose-dependent way. SST inhibition was not antagonized by cyclosomatostatin (cyclo [7-aminoheptanoyl-Phe-D-Trp-Lys-Thr(Bzl)]), a putative SST antagonist, which in contrast behaved as a partial agonist. When the chemical drive to respiration was increased, by lowering the pH of the brain stem superfusion medium from 7.4 to 7.3, the inhibitory effect of SST on respiratory frequency was potentiated. These results suggest an interaction between SST and respiratory central chemoreception in new-born mouse.
Laboratory of Neural Systems, Biology Department, Faculty of Chemistry and Biology, Universidad de Santiago de Chile, USACH, Alameda 3363, Casilla 40 Correo 33, Santiago, Chile. illona@lauca.usach.cl
Isabel
I
Llona
Estíbaliz
E
Ampuero
Jaime L
JL
Eugenín
D000818:Animals; D000831:Animals, Newborn; D001933:Brain Stem / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006728:Hormones / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D051379:Mice; D012119:Respiration / Q000187:drug effects*; D013004:Somatostatin / Q000494:pharmacology*; D013116:Spinal Cord / Q000187:drug effects; D018709:Statistics, Nonparametric
D006728:Hormones; D013004:Somatostatin