Premium
Inverse gradient of nitrergic and purinergic inhibitory cotransmission in the mouse colon
Author(s) -
Mañé N.,
Viais R.,
MartínezCutillas M.,
Gallego D.,
CorreiadeSá P.,
Jiménez M.
Publication year - 2016
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/apha.12599
Subject(s) - purinergic receptor , neurotransmission , inhibitory postsynaptic potential , electrical impedance myography , chemistry , acetylcholine , electrophysiology , cholinergic , endocrinology , medicine , nitric oxide , vasodilation , receptor , adenosine
Aim Gastrointestinal smooth muscle relaxation is accomplished by the neural corelease of ATP or a related purine and nitric oxide. Contractions are triggered by acetylcholine and tachykinins. The aim of this work was to study whether regional differences in neurotransmission could partially explain the varied physiological roles of each colonic area. Methods We used electrophysiological and myography techniques to evaluate purinergic (L‐ NNA 1 m m incubated tissue), nitrergic ( MRS 2500 0.3 μ m incubated tissue) and cholinergic neurotransmission (L‐ NNA 1 m m and MRS 2500 0.3 μ m incubated tissue) in the proximal, mid and distal colon of CD 1 mice ( n = 42). Results Purinergic electrophysiological responses elicited by single pulses (28 V) were greater in the distal ( IJP f MAX = −35.3 ± 2.2 mV), followed by the mid ( IJP f MAX = −30.6 ± 1.0 mV) and proximal ( IJP f MAX = −11.7 ± 1.1 mV) colon. In contrast, nitrergic responses decreased from the proximal colon ( IJP s MAX = −11.4 ± 1.1 mV) to the mid ( IJP s MAX = −9.1 ± 0.4 mV), followed by the distal colon ( IJP s MAX = −1.8 ± 0.3 mV). A similar rank of order was observed in neural mediated inhibitory mechanical responses including electrical field stimulation‐mediated responses and neural tone. ADP β s concentration–response curve was shifted to the left in the distal colon. In contrast, Na NP responses did not differ between regions. Cholinergic neurotransmission elicited contractions of a similar amplitude throughout the colon. Conclusion An inverse gradient of purinergic and nitrergic neurotransmission exists through the mouse colon. The proximal and mid colon have a predominant nitrergic neurotransmission probably due to the fact that their storage function requires sustained relaxations. The distal colon, in contrast, has mainly purinergic neurotransmission responsible for the phasic relaxations needed to propel dehydrated faeces.