Histamine decreases left ventricular contractility in normal human subjects.
To determine whether histamine alters human left ventricular contractility we measured heart rate, calibrated carotid arterial pressure, and left ventricular dimensions (echocardiogram) in nine healthy volunteers. We assessed baseline contractility using the end-systolic pressure-dimension relationship and the end-systolic meridional wall stress-rate-corrected velocity of circumferential fiber shortening relationship determined over a wide range of afterloads using phenylephrine and nitroprusside infusions. We then infused histamine for 3-5 min at a dose predetermined to decrease mean arterial pressure by 20%, both before and after H1 receptor antagonist pretreatment (diphenhydramine 50 mg i.v.). Histamine decreased end-systolic pressure but, unlike an equally hypotensive infusion of nitroprusside, did not decrease end-systolic dimension or increase fractional shortening. Histamine also decreased velocity of circumferential fiber shortening at the same end-systolic meridional wall stress as controls (P < 0.05). These effects of histamine were inhibited by H1 antagonist pretreatment. We conclude that the dominant effect of histamine on the human heart is to decrease left ventricular contractility and that this decrease in contractility is dependent, at least partially, on H1-receptor activation.
University of British Columbia, Division of Cardiology, St. Paul's Hospital, Vancouver, Canada.
D J
DJ
Cooper
C R
CR
Thompson
K R
KR
Walley
R P
RP
Gillis
P E
PE
Wolinski-Walley
R R
RR
Schellenberg
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D004280:Dobutamine / Q000494:pharmacology; D004452:Echocardiography; D004562:Electrocardiography; D006352:Heart Ventricles / Q000187:drug effects; D006632:Histamine / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D016277:Ventricular Function, Left
D006634:Histamine H1 Antagonists; D004280:Dobutamine; D006632:Histamine