Clinical physiology and functional imaging
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Clin Physiol Funct Imaging · Nov 2011
Randomized Controlled TrialThe effect of phenylephrine on arterial and venous cerebral blood flow in healthy subjects.
Sympathetic regulation of the cerebral circulation remains controversial. Although intravenous phenylephrine (PE) infusion reduces the near-infrared spectroscopy (NIRS)-determined measure of frontal lobe oxygenation (S(c) O(2) ) and increases middle cerebral artery mean blood velocity (MCA V(mean) ), suggesting α-adrenergic-mediated cerebral vasoconstriction, this remains unconfirmed by evaluation of arterial and venous cerebral blood flow. ⋯ These findings confirm that PE induces a reduction in S(c) O(2) measured by NIRS and causes an increase in MCA V(mean) indicative of cerebral arterial vasoconstriction, although ICA was preserved and IJV increased. These results suggest that a decrease in S(c) O(2) during infusion of PE reflects an altered cerebral contribution of arterial versus venous blood to the NIRS signal, although we cannot rule out that an effect of PE on skin blood flow is important.
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Clin Physiol Funct Imaging · Nov 2011
Randomized Controlled TrialTRPV1 and TRPA1 stimulation induces MUC5B secretion in the human nasal airway in vivo.
Nasal transient receptor potential vanilloid 1 (TRPV1) stimulation with capsaicin produces serous and mucinous secretion in the human nasal airway. The primary aim of this study was to examine topical effects of various TRP ion channel agonists on symptoms and secretion of specific mucins: mucin 5 subtype AC (MUC5AC) and B (MUC5B). ⋯ Agonists of TRPV1 and TRPA1 induced MUC5B release in the human nasal airways in vivo. These findings may be of relevance with regard to the regulation of mucin production under physiological and pathophysiological conditions.