Regulation of enteric nervous system in the proximal and distal parts of the normal human pyloric sphincter--in vitro study.
OBJECTIVE
The structure of the pyloric sphincter (PS) muscle has recently been shown to divide into two parts (proximal and distal parts). To clarify the functional differences in the human PS between proximal and distal parts, we investigated the enteric nerve responses in normal proximal and distal PS specimens.


METHODS
Normal PS specimens derived from 20 patients with early gastric cancer (13 men and 7 women aged from 50 to 64 years, average 58.2 years) were used. These PS muscles were divided into 2 parts [1/2 oral site of PS; proximal part (PPS; n=26), 1/2 anal site of PS; distal part (DPS; n=24)]. A mechanographic technique was used to evaluate in vitro muscle strip responses to electrical field stimulation (EFS) before and after treatment with various autonomic nerve blockers.


RESULTS
Findings were: (1) Response to EFS before blockade of the adrenergic and cholinergic nerves: Excitatory responses (contraction reaction) via cholinergic nerves in the PPS were regulated more predominantly than in the DPS. Inhibitory responses (relaxation reaction) via adrenergic nerves in the DPS were regulated more predominantly than in the PPS. (2) Response to EFS after blockade of the adrenergic and cholinergic nerves: Excitatory responses (contraction reaction) via non-adrenergic non-cholinergic (NANC) excitatory nerves in the PPS were regulated significantly more than in the DPS (P = 0.0439). Inhibitory responses (relaxation reaction) via NANC inhibitory nerves in the DPS were also regulated significantly more than in the PPS (P = 0.0439). (3) EFS response in the pylorus was blocked by tetrodotoxin.


CONCLUSIONS
There are differences between the PPS and DPS in the regulation of the enteric nervous system. Contraction reaction via excitatory nerves, especially cholinergic nerves, was mainly involved in the regulation of enteric nerve responses to EFS in the PPS. Relaxation reaction via inhibitory nerves, especially NANC inhibitory nerves, was mainly involved in the regulation of enteric nerve responses to EFS in the DPS.
Tomita
Ryouichi
R
Department of Surgery, Nippon Dental University School of Dentistry at Tokyo, Japan. rtomita-ndus@mvg.biglobe.ne.jp
Igarashi
Seigo
S
Fijisaki
Shigeru
S
Koshinaga
Tugumichi
T
Tanjoh
Katsuhisa
K
D018674:Adrenergic Antagonists / Q000494:pharmacology; D000320:Adrenergic Fibers / Q000187:drug effects; D018680:Cholinergic Antagonists / Q000494:pharmacology; D002799:Cholinergic Fibers / Q000187:drug effects; D004558:Electric Stimulation; D017615:Enteric Nervous System / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D011706:Pyloric Antrum / Q000294:innervation*
D018674:Adrenergic Antagonists; D018680:Cholinergic Antagonists