S Chakder

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Recent investigations have suggested carbon monoxide (CO) as a putative messenger molecule. Although several studies have implicated the heme oxygenase (HO) pathway, responsible for the endogenous production of CO, in the neuromodulatory control of the internal anal sphincter (IAS), its exact role is not known. Nitric oxide, produced by neuronal nitric(More)
Unlike its effects on the rest of the GI tract, the effects of pituitary adenylate cyclase-activating peptide (PACAP) on the internal anal sphincter (IAS) are not known. We examined the actions of PACAP-38 (here PACAP) and PACAP-27 on the basal IAS tone of circular smooth muscle strips before and after the administration of different neurohumoral(More)
A significant interaction between vasoactive intestinal polypeptide (VIP) and nitric oxide (NO) has been reported in neurotransmission of the gastrointestinal tract, including the internal anal sphincter (IAS). The exact site of this NO release from the IAS in response to VIP is not known. Studies were carried out to determine the site of this VIP-induced(More)
In summary, PACAP exerts a biphasic effect (an initial contraction followed by a relaxation) in the IAS. The initial contractile effect with higher concentrations of PACAP was found to be mediated by the activation of PACAP receptor at the substance P-containing nerve terminals. The PACAP receptor(s) responsible for the inhibitory action of the neuropeptide(More)
Nitric oxide and vasoactive intestinal polypeptide (VIP) are important inhibitory neurotransmitters mediating relaxation of the internal anal sphincter. The location and coexistence of these two neurotransmitters in the internal anal sphincter has not been examined. We performed a double-labeling study to examine the coexistence of nitric oxide synthase and(More)
Despite its widespread distribution and significance in the gut, the role of pituitary adenylate cyclase-activating peptide (PACAP) in internal anal sphincter (IAS) relaxation has not been examined. This study examined the role of PACAP in nonadrenergic noncholinergic (NANC) nerve-mediated relaxation of IAS smooth muscle. Circular smooth muscle strips from(More)
The exact role of the hypogastric nerve (HGN) in the regulation of basal internal anal sphincter pressures (IASP) and rectoanal reflex (RAR)-induced internal anal sphincter (IAS) relaxation is not known. The studies were performed to investigate the effect of electrical stimulation of HGN (HGNS) on IASP and RAR-induced fall in IASP, simultaneously record(More)
We performed functional studies on the opossum internal anal sphincter (IAS) smooth muscle strips and receptor binding studies in the IAS smooth muscle membranes to examine the influence of: human calcitonin gene-related peptide (CGRP)-(8-37) on the fall in IAS tension caused by human CGRP I and CGRP II and on [125I]human CGRP I binding on the IAS smooth(More)
The present study was carried out to investigate the effects of porcine galanin-(1-29), N-terminal fragment galanin-(1-10), C-terminal fragment galanin-(15-29), and the middle fragment galanin-(7-16) on the spontaneous tension of the opossum internal anal sphincter and on the decrease in the resting internal anal sphincter tension in response to neural(More)
The effects of calcitonin gene-related peptide (CGRP) I(alpha) (human), CGRP II(beta) (human), CGRP (rat), and [Tyr0]-CGRP (rat) on the resting tone of opossum internal anal sphincter (IAS) were studied. Different CGRPs identified above produced a concentration-dependent fall in the resting tension of the IAS. CGRP II (human) was most potent, while(More)
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