Effect of exogenous glutamate and N-Methyl-D-aspartic acid on spontaneous activity of isolated human ureter.
OBJECTIVE
While the neurotransmitter role of glutamate in the gastrointestinal tract has been shown, its effects on smooth muscle of the human ureter have not previously been investigated. In our study we have investigated the effects of exogenous glutamate on the spontaneous activity of isolated human ureter, taken from 14 adult patients after nephrectomy.


METHODS
The segment of ureter, excised 3 cm distal from the pyeloureteral junction, was isolated in an organ bath. Both longitudinal tension and intraluminal pressure of the segment were recorded simultaneously.


RESULTS
Glutamate administered in the lumen of the isolated ureteral segments (7.8 x 10(-7) M/L-3.5 x 10(-2) M/L) was ineffective. When added to the isolated organ bath from the serous side of the ureteral segment, glutamate (7.9 x 10(-6) M/L-10.6 x 10(-3) M/L) and N-Methyl-D-aspartic acid (NMDA) (9.1 x 10(-8) M/L-3.1 x 10(-5) M/L) produced a concentration-dependent increase in spontaneous activity of the isolated preparations, while kainic acid (6.3 x 10(-8) M/L-10.5 x 10(-5) M/L) and (+/-)-trans-1-Aminocyclopentane-trans-1,3-dicarboxylic acid (ACPD) (7.7 x 10(-8) M/L -6.5 x 10(-5) M/L) were ineffective.


CONCLUSIONS
The results of our study suggest that an excitatory neurotransmitter glutamate stimulates spontaneous activity of the human ureter through activation of NMDA ionotropic receptors, located on smooth muscle cells or intramural nerve fibers.
Jankovic
Slobodan M
SM
Pharmacology Department, Medical Faculty, University of Kragujevac, Kragujevac, Serbia. slobnera@eunet.yu
Jankovic
Snezana V
SV
Stojadinovic
Dobrivoje
D
Jakovljevic
Mihajlo
M
Milovanovic
Dragan
D
D000328:Adult; D000368:Aged; D003515:Cycloleucine / Q000031:analogs & derivatives; D005260:Female; D018698:Glutamic Acid / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D007608:Kainic Acid; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000502:physiology*; D016202:N-Methylaspartate / Q000502:physiology; D014513:Ureter / Q000502:physiology*
D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D018698:Glutamic Acid; D016202:N-Methylaspartate; D007608:Kainic Acid