Effect of Diabetes on Cooling-induced Detrusor Muscle Contraction: Mediation Via Rho-kinase Activation

Background: Overweight is associated with a high prevalence of hypertension. The mechanisms linking overweight to blood pressure increase remain unclear. We hypothesized that vascular Rho-kinase activation contributes to blood pressure increase in overweight by involving TNF-α and TLR4. Methods: C57/BL6 mice fed a high-fat diet for 2 weeks were used to induce overweight associated blood pressure increase. Additional treatment in overweight and normal weight mice contained Rho-kinase inhibitors (fasudil and pravastatin; n=7/all groups), etanercept and TNFR1 and TLR4 null-mice. Microvascular studies were performed in a wire myograph and arterial blood pressure measured with a carotid catheter. Rho-kinase activity was determined in small mesenteric arteries of all groups. Inflammatory ligands such as TNF-alpha and free fatty acids were determined. Effects of TNF-alpha and TLR4 ligand LPS and palmitic acid on Rho-kinase activity and were determined ex vivo in mesenteric arteries and in in vivo. Results: Overweight mice had higher blood pressure (Delta: 9±2 mmHg) and vasoconstriction as normal weight mice. Small mesenteric arteries of overweight mice had a 50% higher Rho-kinase activity as normal weight mice. Ex vivo treatment with the Rho-kinase inhibitor Y-27632 reversed vasoconstriction of mesenteric arteries of overweight mice to constriction level in normal weight mice. In vivo treatment with the Rho-kinase inhibitor fasudil or pravastatin along with high-fat diet abolished the overweight associated blood pressure increase and enhanced vasoconstriction. TNF-alpha and TLR4 ligand free fatty acid were enhanced in overweight mice. TNF-alpha and TLR4 ligand LPS and palmitic acid increased Rho-kinase activity in mesenteric arteries. Use of etenercept, TNFR1 and TLR4 null-mice in the overweight model prevented blood pressure increase, vasoconstriction and Rho-kinase activation. All described effects were independent of adiposity. Conclusion: These results indicated that in diet-induced overweight vascular Rho-kinase activation is a key element of increased blood pressure and vasoconstriction. Potential activator of Rho-kinase are mediated by inflammatory factors including TLR4 ligands and TNF-alpha.

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Abstract P2017: Angiotensin-Induced Constriction via Rho Kinase Activation in Pressure-Overloaded Rat Thoracic Aortas

Hypertension ◽

10.1161/hyp.74.suppl_1.p2017 ◽

2019 ◽

Vol 74 (Suppl_1) ◽

Author(s):

Yuka Terada ◽

Katsutoshi Yayama

Keyword(s):

Rho Kinase ◽

Kinase Activation

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NK2 receptor-mediated detrusor muscle contraction involves Gq/11-dependent activation of voltage-dependent Ca2+ channels and the RhoA-Rho kinase pathway

AJP Renal Physiology ◽

10.1152/ajprenal.00106.2019 ◽

2019 ◽

Vol 317 (5) ◽

pp. F1154-F1163 ◽

Cited By ~ 1

Author(s):

Bálint Dér ◽

Péter József Molnár ◽

Éva Ruisanchez ◽

Petra Őrsy ◽

Margit Kerék ◽

...

Keyword(s):

Urinary Bladder ◽

Rho Kinase ◽

Detrusor Muscle ◽

Dependent Manner ◽

Contraction Force ◽

Rhoa Activity ◽

Voltage Dependent ◽

Intracellular Ca ◽

Nk2 Receptor ◽

Kinase Pathway

Tachykinins (TKs) are involved in both the physiological regulation of urinary bladder functions and development of overactive bladder syndrome. The aim of the present study was to investigate the signal transduction pathways of TKs in the detrusor muscle to provide potential pharmacological targets for the treatment of bladder dysfunctions related to enhanced TK production. Contraction force, intracellular Ca2+ concentration, and RhoA activity were measured in the mouse urinary bladder smooth muscle (UBSM). TKs and the NK2 receptor (NK2R)-specific agonist [β-Ala8]-NKA(4–10) evoked contraction, which was inhibited by the NKR2 antagonist MEN10376. In Gαq/11-deficient mice, [β-Ala8]-NKA(4–10)-induced contraction and the intracellular Ca2+ concentration increase were abolished. Although Gq/11 proteins are linked principally to phospholipase Cβ and inositol trisphosphate-mediated Ca2+ release from intracellular stores, we found that phospholipase Cβ inhibition and sarcoplasmic reticulum Ca2+ depletion failed to have any effect on contraction induced by [β-Ala8]-NKA(4–10). In contrast, lack of extracellular Ca2+ or blockade of voltage-dependent Ca2+ channels (VDCCs) suppressed contraction. Furthermore, [β-Ala8]-NKA(4–10) increased RhoA activity in the UBSM in a Gq/11-dependent manner and inhibition of Rho kinase with Y-27632 decreased contraction force, whereas the combination of Y-27632 with either VDCC blockade or depletion of extracellular Ca2+ resulted in complete inhibition of [β-Ala8]-NKA(4–10)-induced contractions. In summary, our results indicate that NK2Rs are linked exclusively to Gq/11 proteins in the UBSM and that the intracellular signaling involves the simultaneous activation of VDCC and the RhoA-Rho kinase pathway. These findings may help to identify potential therapeutic targets of bladder dysfunctions related to upregulation of TKs.

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