Document Detail


Effect of intravenous infusion of an alpha-adrenergic blocking agent on the haemodynamic changes in human masseter muscle induced by cold pressor stimulation.
MedLine Citation:
PMID:  10348358     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study evaluated the effect of intravenous infusion of a non-selective alpha-adrenergic blocking agent on masseter muscle haemodynamics induced by 4 degrees C cold pressor stimulation (CPS) of the right foot and ankle, which reportedly evokes a rapidly increasing sympathetic nerve activity in human skeletal muscle. Nine healthy non-smoking males (mean age 23.7+/-2.1 year) with no history of chronic muscle pain or migraine participated. The haemoglobin (Hb) concentration in the right masseter was continuously recorded by non-invasive, near-infrared spectroscopy. Heart rate and blood pressure were also recorded. The experiment involved the following sequence: (1) a placebo (physiological saline) with a CPS trial; (2) a 30-sec maximal voluntary clenching (MVC)-only trial; and (3) an alpha-adrenergic blocking agent with a CPS trial. The saline and drug trials each involved continuous recording for 1 min before, 2 min during and 5 min after the CPS. Physiological saline (20 ml) or phentolamine mesylate (20 ml) were infused at the rate of 2 ml/min. This infusion was begun 15 min before baseline recording and participants were not aware which solution (saline or phentolamine) was being infused. For the MVC trial, each participant performed a 30-sec MVC of his jaw-closing muscles followed by a 15-min rest between each trial. The individual Hb data were adjusted so that the baseline at the beginning of the experiment was equal to zero and all data were normalized as a percentage of the individual's highest absolute Hb change seen after the MVC. The mean baseline Hb concentrations 1 min before CPS were significantly higher in the alpha-blocker trial (83.6%) than in the placebo saline trial (P < 0.001). The change in mean Hb concentration from baseline during CPS in the alpha-blocker trial was significantly less than in the placebo trial (P = 0.006). Mean heart rate before CPS was also significantly higher in the alpha-blocker trial (85.2 beats/min) than in the placebo trial (69.6 beats/min) (P < 0.001). There were no significant differences in the mean systolic and diastolic blood pressures between the placebo and alpha-blocker trials in any time period. The results suggest that non-selective alpha-adrenoceptor blockade increases the blood volume in the masseter muscle. This change might be due to a combination of peripheral vasodilation and an increase in cardiac output.
Authors:
K Maekawa; T Kuboki; T Miyawaki; M Shimada; A Yamashita; G T Clark
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Publication Detail:
Type:  Clinical Trial; Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Archives of oral biology     Volume:  44     ISSN:  0003-9969     ISO Abbreviation:  Arch. Oral Biol.     Publication Date:  1999 Apr 
Date Detail:
Created Date:  1999-07-02     Completed Date:  1999-07-02     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0116711     Medline TA:  Arch Oral Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  319-27     Citation Subset:  D; IM    
Affiliation:
Department of Fixed Prosthodontics, Okayama University Dental School, Japan. maekawa@dent.okayama-u.ac.jp
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MeSH Terms
Descriptor/Qualifier:
Adrenergic alpha-Antagonists / pharmacology*
Adult
Blood Pressure / drug effects,  physiology
Blood Volume / drug effects
Cardiac Output / drug effects
Cold Temperature / adverse effects*
Heart Rate / drug effects,  physiology
Hemodynamics / drug effects
Hemoglobins / analysis
Humans
Infusions, Intravenous
Male
Masseter Muscle / drug effects*,  physiology
Muscle Contraction / drug effects
Oxygen / blood
Phentolamine / pharmacology*
Physical Stimulation
Placebos
Single-Blind Method
Spectroscopy, Near-Infrared
Vasodilator Agents / pharmacology
Chemical
Reg. No./Substance:
0/Adrenergic alpha-Antagonists; 0/Hemoglobins; 0/Placebos; 0/Vasodilator Agents; 50-60-2/Phentolamine; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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