Function of beta 2-adrenergic receptors in chronic localized myalgia.
OBJECTIVE
To investigate alteration of beta 2-adrenergic receptor (beta 2 AR) function in chronic localized myalgia subjects by evaluating levels of the beta 2 AR second messenger, cyclic adenosine monophosphate (cAMP), in mononuclear cells after beta AR-agonist stimulation.


METHODS
Eleven chronic localized myalgia subjects and 21 matched healthy controls participated in this study. Peripheral blood (30 cc) was drawn from the subjects' anterocubital vein. Mononuclear cells were isolated from the total blood by using the Ficoll-Hypaque gradient technique. Basal and stimulated intracellular cAMP levels were determined by enzyme immunoassay using a commercially available kit. Aliquots of 5 x 10(6) cells were incubated with or without stimulation of the beta AR-agonist isoproterenol for 5 minutes. Five different concentrations of isoproterenol (10(-3) M to 10(-7) M) were utilized. cAMP levels in both groups were tested statistically by a 2-way repeated-measures ANOVA with 2 predictors, group difference and isoproterenol concentration difference. As with isoproterenol stimulation, the cAMP responses to forskolin, which activates adenylyl cyclase directly and produces cAMP, bypassing the cell surface receptors were also measured.


RESULTS
The basal cAMP levels in both groups (myalgia: 0.33 +/- 0.02 pmol/5 x 10(6) cells; control: 0.43 +/- 0.10 pmol/5 x 10(6) cells) were almost identical, and isoproterenol-produced cAMP levels increased dose-dependently in both groups. No significant differences in the mean cAMP levels were observed between the groups (P = .909). Significant increases were observed according to the isoproterenol concentration increase (P < .0001). The cAMP responses to forskolin stimulation also showed no significant group difference (P = .971).


CONCLUSIONS
These results suggest that beta 2 AR function is not different between localized myalgia subjects and healthy individuals.
Maekawa
Kenji
K
Department of Oral and Maxillofacial Rehabilitation, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama, Japan, 700-8525. maekawa@md.okayama-u.ac.jp
Kuboki
Takuo
T
Inoue
Eitoku
E
Inoue-Minakuchi
Mami
M
Suzuki
Koji
K
Yatani
Hirofumi
H
Clark
Glenn T
GT
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology; D000328:Adult; D000704:Analysis of Variance; D016022:Case-Control Studies; D002908:Chronic Disease; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000097:blood; D004305:Dose-Response Relationship, Drug; D005152:Facial Muscles / Q000503:physiopathology*; D005157:Facial Pain / Q000503:physiopathology; D005260:Female; D005356:Fibromyalgia / Q000503:physiopathology*; D006801:Humans; D007545:Isoproterenol / Q000008:administration & dosage / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000201:enzymology; D008297:Male; D009334:Neck Muscles / Q000503:physiopathology*; D018343:Receptors, Adrenergic, beta-2 / Q000502:physiology*; D015290:Second Messenger Systems; D018709:Statistics, Nonparametric
D000318:Adrenergic beta-Agonists; D018343:Receptors, Adrenergic, beta-2; D005576:Colforsin; D000242:Cyclic AMP; D007545:Isoproterenol