1995
DOI: 10.1007/bf00386163
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Effects of inhibitors of enzymatic and cellular pH-regulating systems on central sympathetic chemosensitivity

Abstract: Previous studies in cats using isolated NaCl-CO2 perfusion of the lower brainstem demonstrated an intrinsic chemosensitivity of sympathoexcitatory bulbospinal neurones within the rostroventrolateral medulla (RVLM). In the present experiments, the effects of inhibitors of enzymatic and cellular systems, known to be involved in pH regulation, were investigated. Isolated perfusion of the lower brainstem with CO2-enriched solutions was performed and preganglionic sympathetic nerve activity (SNA) was recorded. Drug… Show more

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Cited by 10 publications
(4 citation statements)
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“…As Na + -dependent Cl -/HCO 3 -seems to play a minor role in the ventrolateral medulla [23,24] either NHE3 itself or further unknown mechanisms could account for this effect. The NHE1 inhibitor EIPA also failed to induce hypercapnic-like nerve fibre activity originating from ventrolateral neurones of the cat [14]. This finding indirectly supports the role of NHE3 as one major NHE subtype within ventrolateral neurones.…”
Section: Discussionmentioning
confidence: 65%
See 1 more Smart Citation
“…As Na + -dependent Cl -/HCO 3 -seems to play a minor role in the ventrolateral medulla [23,24] either NHE3 itself or further unknown mechanisms could account for this effect. The NHE1 inhibitor EIPA also failed to induce hypercapnic-like nerve fibre activity originating from ventrolateral neurones of the cat [14]. This finding indirectly supports the role of NHE3 as one major NHE subtype within ventrolateral neurones.…”
Section: Discussionmentioning
confidence: 65%
“…In fact, regulation of pH i in VLNcs or nucleus tractus solitarius neurones differs from that of neurones within non-chemosensitive brain areas [23,24] as they do not counteract a moderate (∆pH i <0.2 units) intracellular acidosis due to hypercapnia (pCO 2 elevated to 80-100 mmHg) or withdrawal of CO 2 /HCO 3 -amiloride, but not by 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS), pointing to a major contribution of Na + /H + exchange (NHE), while (Na + -dependent) Cl -/HCO 3 -antiport appears to be less involved. Previous in vivo studies show that inhibition of NHE by 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) fails to activate respiration [14], and amiloride stimulates breathing frequency only at high (>1 mol/l) concentrations [30]. However, the inhibitory properties of amiloride or EIPA strongly depend on the subtype of NHE that is expressed.…”
Section: Introductionmentioning
confidence: 98%
“…Microinjections of 100 M ethyl-isopropyl-amiloride (EIPA) into the ventrolateral medulla did not add to preganglionic sympathetic nerve activation elicited by hypercapnic brainstem perfusion in the cat (26). Likewise, cisternal infusion of amiloride between 10 Ϫ5 and 10 Ϫ2 M failed to change the CO 2 sensitivity of pulmonary ventilation in anesthetized rabbits (27,28).…”
Section: Role Of Nhe3 Versus Other Nhe Subtypes In Central Chemosensimentioning
confidence: 96%
“…Whilst there are some clues that NHE is not causally involved in the functioning of central chemosensitivity (König et al ., 1995), inhibition of NHE3 acidifies and activates neurones in the medulla oblongata (Wiemann et al ., 1999). However, only 50% of all subjects with essential hypertension show enhanced NHE activation (Rosskopf et al ., 1993; Siffert et al ., 1995).…”
Section: Discussionmentioning
confidence: 99%