0000000000114129
AUTHOR
Sebastian D. Vulcu
The cAMP Pathway Sensitizes VR1 Expressed in Oocytes from <i>Xenopus laevis</i> and in CHO Cells
The vanilloid receptor 1 (VR1) is a heat-activated cation channel which also responds to capsaicin and other chemical stimuli. Protein kinase C has a stimulatory effect on VR1 activity, either alone or after activation with capsaicin. The influence of the cAMP-signaling pathway on the effects of capsaicin is controversial. To clarify this, the actions of capsaicin and the modulatory effects of forskolin, pCPT-cAMP, and isobutylmethylxanthine were studied in <i>Xenopus laevis</i> oocytes expressing rat VR1 and in CHO cells expressing human VR1. Capsaicin activated the VR1 channel and increased the intracellular calcium concentration. The effects of capsaicin were enhanced by fors…
Proton conductance of human transient receptor potential-vanilloid type-1 expressed in oocytes of Xenopus laevis and in Chinese hamster ovary cells.
Transient receptor potential-vanilloid type-1 (TRPV1) is a ligand-gated cation channel with preference for divalent cations, especially Ca(2+) (sequence of conductances: Ca(2+)Mg(2+)Na(+) approximately/= K(+) approximately/= Cs(+)). In the present study, the two-electrode voltage-clamp technique was used on oocytes of Xenopus laevis expressing TRPV1 to evaluate whether human TRPV1 also conducts protons. In medium devoid of K(+), Na(+), Mg(2+), and Ca(2+), capsaicin 1 microM induced a significant inward current (62% of the current in physiological medium). The effects of capsaicin were abolished in the presence of capsazepine 3 microM. The capsaicin-induced currents in medium devoid of Na(+)…
Differences in the nitric oxide/soluble guanylyl cyclase signalling pathway in the myocardium of neonatal and adult rats
Abstract The effects of a nitric oxide-donor, S -nitroso- N -acetylpenicillamine, and a direct activator of soluble guanylyl cyclase, 3-(5′-hydroxymethyl-2′-furyl)-1-benzyl indazole (YC-1), on force of contraction ( F c ) and L-type Ca 2+ currents ( I Ca(L) ) were investigated in myocardial preparations from neonatal and adult rats. Since hearts from adult and neonatal animals contained 160 and 47 mg/100 g wet weight myoglobin, respectively, its possible interaction with both drugs was also investigated. Both S -nitroso- N -acetylpenicillamine (100 μM) and YC-1 (30 μM) were ineffective in myocardial preparations from adult rats but reduced the magnitude of I Ca(L) and F c in preparations fr…
Monovalent cation conductance in Xenopus laevis oocytes expressing hCAT-3
hCAT-3 (human cationic amino acid transporter type three) was investigated with both the two-electrode voltage clamp method and tracer experiments. Oocytes expressing hCAT-3 displayed less negative membrane potentials and larger voltage-dependent currents than native or water-injected oocytes did. Ion substitution experiments in hCAT-3-expressing oocytes revealed a large conductance for Na + and K + . In the presence of l-Arg, voltage-dependent inward and outward currents were observed. At symmetrical (inside/outside) concentrations of l-Arg, the conductance of the transporter increased monoexponentially with the l-Arg concentrations; the calculated Vmax and KM values amounted to 8.3 AS and…
Troponin I concentrations of shed blood might influence monitoring of myocardial injury after coronary operations.
Abstract In a prospective study we evaluated the concentration of cardiac troponin I (cTnI) and creatine kinase activities (CK) in shed mediastinal blood in the early postoperative period after coronary artery bypass grafting (CABG). Forty seven patients who underwent first time elective CABG were studied. CTnI levels and CK activities in arterial blood and shed mediastinal blood were measured after admission to the intensive care unit (ICU) and 6 h after unclamping the aorta. Mediastinal shed blood samples were drawn from 23 patients (group A) before the filter of the cardiotomy reservoir and from 24 patients (group B) behind. Additionally, both markers were measured in blood samples colle…