The influence of Type A behavior pattern on the response to the panicogenic agent CCK-4.
OBJECTIVE
Review of the literature equivocally suggests that subjects with Type A behavioral pattern (TABP) compared to subjects with Type B behavioral pattern display an increased sympathetic activity, a condition associated with sudden cardiac death. The objective of this study was to determine whether healthy subjects classified as Type A or Type B differed in their reactivity to the beta 1 and beta 2 receptor agonist isoproterenol and to the panicogenic agent cholecystokinin-tetrapeptide (CCK-4). By comparing reactivity to CCK-4 after pretreatment with placebo or propranolol, a beta 1 and beta 2 receptor antagonist, the role of the beta adrenergic system in the hypothesized increased response of Type A subjects to CCK-4 was also assessed.


METHODS
The study used a randomized, double-blind, placebo-controlled design. Twenty-seven Type A or B subjects were included in the study. The reactivity to isoproterenol was assessed with the CD25 of isoproterenol (i.e., the intravenous dose of isoproterenol necessary to increase the heart rate of 25 bpm). The panic symptom response and the cardiovascular response to bolus injection of 50 microg of CCK-4 was assessed in subjects pretreated with either propranolol or placebo infusions prior to the CCK-4 challenge. An additional group of subjects was recruited and these subjects received a placebo infusion pretreatment before an injection of placebo.


RESULTS
The CD25 was significantly greater in Type A subjects than in Type B subjects. No difference was found among the groups on behavioral sensitivity to the CCK-4 challenge. However, CCK-4-induced maximum increase in heart rate was greater in Type A subjects.


CONCLUSIONS
Our finding that Type A subjects exhibited greater CD25 of isoproterenol and greater increases in heart rate following CCK-4 administration compared to Type B subjects suggests that peripheral beta-receptor sensitivity may be increased in individuals with TABP.
Le Mellédo
J M
JM
Department of Psychiatry, University of Alberta, 1E7.26 Mackenzie Centre, 8440 112 Street, Edmonton, Alberta, Canada T6G 2B7. jean-michel.lemelledo@ualberta.ca
Arthur
H
H
Dalton
J
J
Woo
C
C
Lipton
N
N
Bellavance
F
F
Koszycki
D
D
Boulenger
J P
JP
Bradwejn
J
J
D000318:Adrenergic beta-Agonists / Q000009:adverse effects; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007545:Isoproterenol / Q000009:adverse effects; D008297:Male; D016584:Panic Disorder / Q000139:chemically induced / Q000523:psychology*; D010551:Personality / Q000187:drug effects*; D011433:Propranolol / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D013758:Tetragastrin / Q000009:adverse effects*; D014434:Type A Personality
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D013758:Tetragastrin; D011433:Propranolol; D007545:Isoproterenol