|
KMID : 0376219710080010107
|
|
Chonnam Medical Journal
1971 Volume.8 No. 1 p.107 ~ p.114
|
|
|
Responses of the isolated longitudinal and circular muscle strips of the rabbit urethra to some autonomic drugs
|
|
|
|
|
Abstract
|
|
|
On the reflex mechanism of micturition, Barrington´s report that reflex contraction of the detrusor muscle is accompanied by reflex relaxation of the internal and external sphincter during the micturition has been generally accepted. However, no definite evidence of existence of the internal vesical sphincter has been provided so far, and its reflex inhibition is still in dispute. Recently Lapides (1958) developed a new concept based on the hydrodynamic principle that the urethra as well as the bladder participate in micturition reflex. But there lacks a detailed report on the autonomic innervation to the urethra, and neural mechanism of the urethra in micturition is not known. To study the autonomic innervation to the urethra, the author has examined the responses of isolated longitudinal and circular muscle strips of the male urethra to some autonomic drugs.
Strips of the longitudinal and circular muscles of the prostatic and cavernous urethra responded with contraction to catecholamine (norepinephrine or epinephrine) and this response was not affected by pretreatment of dichloroisoproterenol, a beta receptor blocking agent, whereas it was completely abolished by pretreatment of regitine or phenoxybenzamine, alpha-receptor blocking agents. The responses of the longitudinal muscle strips of the prostatic urethra to norepinephrine were greater than that of the cavernous urethra. Only the muscle strips taken from the prostatic urethra adjacent to internal urethral orifice responded with contraction to acetylcholine and this response was completely abolished by pretreatment of atropine, a cholinergic blocking agent.
These experimental evidences indicate that the urethra is under adrenergic innervation. These adrenergic nerve fibers cause contraction of longitudinal and circular muscle, and their receptor is of alpha type. Only a part of prostatic urethra adjacent to the bladder neck is under cholinergic innervation, and the cholinergic fibers elicit contraction of longitudinal and circular muscles´ in this part of the prostatic urethra.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|
|