The mechanisms for tachykinin‐induced contractions of the rabbit corpus cavernosum

Abstract

1 This study was designed to investigate the mechanisms for the contractions induced by tachykinins (substance P (SP), neurokinin A (NKA) and neurokinin B (NKB)) in the rabbit corpus cavernosum strips, using fura-PE3¯uorimetry and a-toxin permeabilization. 2 Tachykinins induced contractions in the rabbit corpus cavernosum in a concentration-dependent manner. The potency order was SP4NKA4NKB. 3 The tachykinin-induced contractions were enhanced by phosphoramidon (PPAD), an endopeptidase inhibitor, but not by N o -nitro-L-arginine methylester (L-NAME). ] i elevations were mainly due to the Ca 2+ in¯ux; (3) Tachykinin-induced contractions were mainly mediated through the activation of NK 1 receptor expressed in the rabbit corpus cavernosum smooth muscle, and a ected by the endopeptidase activity and (4) Tachykinins may thus play a role in controlling the corpus cavernosum tone.

TRP Channel Agonists Activate Different Afferent Neuromodulatory Mechanisms in Guinea Pig Urinary Bladder

“…In the present experiments, application of SP (1 μM) mimicked the excitatory effect of AITC on spontaneous contractile activity ( Figures 5A,D ) significantly increasing SBC AUC by 128 ± 48% ( P < 0.01) but only slightly increased baseline tension (5 ± 2%, P < 0.05; Figure 5D , n = 8 strips from five guinea pigs). To determine the role of SP release in AITC induced excitation, bladder strips were pretreated with a combination of neurokinin receptor 1, 2, and 3 antagonists (SR 140333, SR 48968, and SR 142801; 1 μM each) which blocks the excitatory effect of substance P in the guinea pig ileum (Holzer et al, 1998 ; Takahashi et al, 2002 ). The neurokinin receptor antagonists alone ( n = 8 strips from eight guinea pigs) decreased AUC by 33 ± 9% ( P < 0.05), without changing the baseline tension and significantly reduced the SP induced enhancement of SBCs ( n = 8 strips from seven guinea pigs, Figures 3E , 5F,G ).…”

“…Chemicals used in this study include: nitro-oleic acid [OA-NO 2 , a mixture of the two possible regioisomers of the nitroalkene substituent (E)-9- and 10-nitro-octadec-9-enoic acid] synthesized as described previously (Baker et al, 2005 ); oleic acid (30 μM) a non-nitrated fatty acid; capsaicin (CAPS, 1 μM), a TRPV1 agonist; allyl isothiocyanate (AITC, 100 μM), a TRPA1 agonist; diarylpiperazine (DP, 1 μM), a selective TRPV1 antagonist (Ki = 6 nM for inhibition of acid pH evoked responses and 35 nM for inhibition of CAPS evoked responses) (Sculptoreanu et al, 2010 ; Artim et al, 2011 ; Zhang et al, 2014a ), a gift from Neurogen Corp (Branford, CT, USA); HC3-03001 (HC3, 10 μM), a selective TRPA1 antagonist (a gift from Hydra Biosciences, Inc., Cambridge, MA); and three neurokinin antagonists (subtypes 1, 2, and 3: SR 140333, SR 48968, and SR 142801, respectively, 1 μM each) (Holzer et al, 1998 ; Takahashi et al, 2002 ; Wise et al, 2007 ), gifts from Sanofi-Aventis LLC (Bridgewater, NJ), were applied in combination. All other agents: tetrodotoxin (TTX, 1 μM), lanthanum (III) chloride heptahydrate (La 3+ , 50 μM), 1-oleoyl-2-acetyl-sn-glycerol (OAG, 50 μM), human α calcitonin gene-related peptide (CGRP, 100 nM), olcegepant (BIBN, 25 μM), substance P (SP, 1 μM), prostaglandin E 2 (500 nM) and indomethacin (INDO, 500 nM) were obtained from Sigma Aldrich (St. Louis, MO) or Tocris (Bristol, UK).…”

Using gene chips to identify organ‐specific, smooth muscle responses to experimental diabetes: potential applications to urological diseases

“…Also, there was an increase in gene expression for both the tachykinin 1 and 3 receptor subtypes. The influence of tachykinins on corporal myocyte function has not been extensively studied, and there are species differences in tachykinin‐induced effects on these receptor subtypes and their effect on corporal myocyte contractility [60,61]. Nonetheless, increased expression of these might correlate with altered corporal myocyte function, and perhaps, altered erectile function leading to ED.…”

Ca 2+ SENSITIZATION IN CONTRACTION OF HUMAN BLADDER SMOOTH MUSCLE

“…Permeabilization of the smooth muscle cell membrane was done using ␣-toxin according to the method described by Takahashi et al 10 Small strips about 0.5 mm wide and 1.0 mm long were mounted between 2 tungsten wires, of which 1 was fixed, while the other was attached to a force transducer (UL2, Minebea Co., Ltd., Osaka, Japan). These strips were permeabilized in relaxing solution composed of 100 mM potassium methansulphonate, 2.2 mM Na 2 adenosine triphosphate, 3.38 mM MgCl 2 , 10 mM ethyleneglycol-bis (␤-aminoethylether)-NЈ, NЈ, NЈ, NЈ-tetra acetic acid (EGTA), 10 mM creatine phosphate and 20 mM tris-maleate 20 (pH 6.8) containing 5,000 U ml Ϫ1 Staphylococcus aureus ␣-toxin for 45 to 60 minutes.…”