Kinetic characteristics of alpha 1-adrenergic contractions in human corpus cavernosum smooth muscle.
Kinetic studies were conducted on the contractile response elicited by phenylephrine (PE) activation of the alpha 1-adrenergic receptor subtype in vascular smooth muscle isolated from the corpus cavernosum of impotent men. PE-induced contractions were separated into distinct phasic and tonic components, and the tonic portion was analyzed using a first-order rate equation to determine the maximal rate constant for onset of contraction (kobs max) and the maximum amplitude of the steady-state contractile response (Req max). The kobs max value in tissues from insulin-dependent diabetic patients was significantly greater than that in tissues from either noninsulin-dependent diabetics or nondiabetics. Additionally, the mean kobs max value in older patients (60-70 yr) was significantly greater than the mean kobs max value in younger patients (32-59 yr). Significant diabetes-related, but not age-related, alterations were also found in Req max. The observed changes in contractility resulted in dramatic age- and pathology-dependent alterations in the initial rate and/or magnitude of PE-induced response generation. These kinetic studies extend our previous observations at steady state and provide further evidence for heightened corporal tissue tone in the etiology of erectile dysfunction.
Christ
G J
GJ
Department of Urology, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, New York 10461.
Schwartz
C B
CB
Stone
B A
BA
Parker
M
M
Janis
M
M
Gondre
M
M
Valcic
M
M
Melman
A
A
D000375:Aging / Q000502:physiology; D000704:Analysis of Variance; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology; D006801:Humans; D007700:Kinetics; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology*; D010409:Penile Diseases / Q000503:physiopathology; D010410:Penile Erection; D010413:Penis / Q000098:blood supply*; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D014189:Transsexualism / Q000503:physiopathology; D014661:Vasoconstriction
D011942:Receptors, Adrenergic, alpha