Recently, we showed that renal afferent neurons exhibit a unique firing pattern, i.e., predominantly sustained firing, upon stimulation. Pathological conditions such as renal inflammation likely alter excitability of renal afferent neurons. Here, we tested whether the proinflammatory chemokine CXCL1 alters the firing pattern of renal afferent neurons. Rat dorsal root ganglion neurons (Th11-L2), retrogradely labeled with dicarbocyanine dye, were incubated with CXCL1 (20 h) or vehicle before patchclamp recording. The firing pattern of neurons was characterized as tonic, i.e., sustained action potential (AP) firing, or phasic, i.e., Ͻ5 APs following current injection. Of the labeled renal afferents treated with vehicle, 58.9% exhibited a tonic firing pattern vs. 7.8%, in unlabeled, nonrenal neurons (P Ͻ 0.05). However, after exposure to CXCL1, significantly more phasic neurons were found among labeled renal neurons; hence the occurrence of tonic neurons with sustained firing upon electrical stimulation decreased (35.6 vs. 58.9%, P Ͻ 0.05). The firing frequency among tonic neurons was not statistically different between control and CXCL1-treated neurons. However, the lower firing frequency of phasic neurons was even further decreased with CXCL1 exposure [control: 1 AP/600 ms (1-2) vs. CXCL1: 1 AP/600 ms (1-1); P Ͻ 0.05; median (25th-75th percentile)]. Hence, CXCL1 shifted the firing pattern of renal afferents from a predominantly tonic to a more phasic firing pattern, suggesting that CXCL1 reduced the sensitivity of renal afferent units upon stimulation. chemokine; CXCL1; renal afferent nerve; voltage-gated sodium channel; tonic; phasic; firing pattern OBSERVATIONS IN PATIENTS with renal failure and/or hypertension who were nephrectomized (7, 17) strongly suggest that renal sensory afferent innervation increases sympathetic-mediated vasoconstriction. Moreover, sympathetic nerve activity in patients after renal transplantation was only normalized with concomitant bilateral nephrectomy (17). Additional work in experimental models indicated (21, 23) that efferent neurogenic influences on cardiac pathology in renal insufficiency are mediated by renal afferent nerve activity (1).In experimental animals, afferent innervation of the kidney was reported to contribute to the sustained blood pressure increases when renal structural damage was present (3, 46). In contrast, renal afferent nerves were described to act protectively against salt-sensitive hypertension and the structural renal damage of high blood pressure (24,44). A more recent study using a more selective method of renal afferent denervation suggests that this might not be the case, but it could be shown that selective renal afferent denervation was able to blunt the development of deoxycorticosterone acetate-salt hypertension (12).Therefore, the benefit of afferent renal nerve ablation for the treatment of refractory hypertension remains controversial (31). In any case, the modulatory influence of afferent renal nerves on sympathetic tone is not well understood....
Freisinger W, Schatz J, Ditting T, Lampert A, Heinlein S, Lale N, Schmieder R, Veelken R. Sensory renal innervation: a kidney-specific firing activity due to a unique expression pattern of voltage-gated sodium channels? Am J Physiol Renal Physiol 304: F491-F497, 2013. First published January 2, 2013; doi:10.1152/ajprenal.00011.2012.-Sensory neurons with afferent axons from the kidney are extraordinary in their response to electrical stimulation. More than 50% exhibit a tonic firing pattern, i.e., sustained action potential firing throughout depolarizing, pointing to an increased excitability, whereas nonrenal neurons show mainly a phasic response, i.e., less than five action potentials. Here we investigated whether these peculiar firing characteristics of renal afferent neurons are due to differences in the expression of voltage-gated sodium channels (Na vs). Dorsal root ganglion (DRG) neurons from rats were recorded by the current-clamp technique and distinguished as "tonic" or "phasic. .67]; P Ͻ 0.05). These findings point to an increased presence of the TTX-resistant Na vs 1.8 and 1.9. Furthermore, tonic neurons exhibited a relatively higher portion of TTX-resistant sodium currents. Interestingly, mRNA expression of TTX-resistant sodium channels was significantly increased in renal, predominantly tonic, DRG neurons. Hence, under physiological conditions, renal sensory neurons exhibit predominantly a firing pattern associated with higher excitability. Our findings support that this is due to an increased expression and activation of TTX-resistant Na vs.
Zeitshrift fur alle Gebiete der Chemischen Technik und des Chemie-Ingenieurwesensi n F o r t f u h r u n g d e r Z e i t s c h r i f t , , A n g e w a n d t e C h e m i e " T e i l B ( f r u h e r , , D i e C h e m i s c h e T e c h n i k " ) u n d d e r , , B e i h e f t e V e r f a h r e n s t e c h n i k z u r V D I -Z e i t s c h r i f t " 25. 'Jabrganp Xr. 2 Stiff 61-112 3ebruar 1953 Edelmetall-Legierungen mit besonderer Bestandigkeit gegen starke Mineralsauren') Von J O H A N N E S SCHATZ, Degussa, Frankfurt am MainZum 80jahrigen Bestehen der Deutschen Gold-und Silber-Scheideansfalt vormals Roessler, Frankfurt a. M.Es werden zwei Gruppen von Edelmetall -Legier ungen beschrieben, die sich bereits seit langem Chemie-Ing.-Te&n. 25. Jahrg. 1953 I Nr. 2 Chemie-1ng.-Tedln. 25. Jahrg. 1953 I Nr. 2
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