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Effects of somatostatin on the control of breathing in humans
Author(s) -
Pedersen Michala E. F.,
Dorrington Keith L.,
Robbins Peter A.
Publication year - 1999
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1999.00289.x
Subject(s) - hypercapnia , somatostatin , hypoxia (environmental) , medicine , tidal volume , pco2 , endocrinology , chemistry , ventilation (architecture) , peripheral , anesthesia , respiratory system , oxygen , mechanical engineering , organic chemistry , engineering
1 Somatostatin depresses the ventilatory response to hypoxia (AHVR). This study sought to determine whether somatostatin also reduced the peripheral chemoreflex sensitivity to hypercapnia, and if so, whether this was related to the reduction in AHVR. 2 Nine subjects completed the study. AHVR and the ventilatory responses to hypercapnia under both hyperoxic and hypoxic conditions were assessed both without and with an infusion of somatostatin (0·5 BsBs 5 mgBs 5 h −1 ). Peripheral (fast) and central (slow) responses to hypercapnia were distingushed by use of a multi‐frequency binary sequence input in end‐tidal P CO2 ( P ET,CO2 ) that included 13 steps into and out of hypercapnia. 3 The acute ventilatory response to a reduction in end‐tidal P O2 ( P ET,O2 ) from 100 to 50 Torr (at a P ET,CO2 of +1·5‐2·0 Torr above normal) was reduced from (mean ± s.e.m.) 16·4 ± 3·3 to 9·5 ± 3·2 l min −1 ( P < 0·005 , Student's t test) by somatostatin. The magnitude of the ensuing hypoxic ventilatory decline was unaltered (8·8 ± 2·7 l min −1 in control vs. 8·0 ± 2·9 l min −1 with somatostatin). 4 The peripheral chemoreflex sensitivity to CO 2 in hypoxia was reduced from 2·42 ± 0·36 to 1·18 ± 0·20 l min −1 Torr −1 ( P < 0·005 ) with somatostatin. The reduction under hyperoxic conditions from 0·75 ± 0·34 to 0·49 ± 0·09 l min −1 Torr −1 did not reach significance. Central chemoreflex sensitivity to CO 2 was unchanged. Changes in peripheral chemoreflex sensitivity to CO 2 in hypoxia correlated with changes in AHVR. 5 We conclude that peripheral chemoreflex sensitivity to CO 2 is reduced by somatostatin, probably via the same mechanism as that by which somatostatin exerts its effects on AHVR.