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Objectives/hypothesis: Different reconstructive options are available for defects following total laryngectomy (TL) and circumferential (CH) or partial hypopharyngectomy (PH). We evaluated the flap success, pharyngocutaneous fistula, and pharyngoesophageal stenosis rates in two groups of patients treated by different policies., Study Design: Comparison between two cohorts of patients treated by TL with PH/CH ± cervical esophagectomy and reconstructed according to different strategies., Methods: Group A (historical) was composed of 89 patients reconstructed by pectoralis major myocutaneous (PMMC), radial forearm (RF), and anterolateral thigh (ALT) flaps. A salivary bypass stent (SBPS) was not routinely applied and left in place for a maximum of 14 days. Forty-four (49%) patients received preoperative radiotherapy/chemoradiotherapy (RT/CRT). Group B (prospective) included 105 patients reconstructed by RF or ALT with long-lasting SBPS left in place for a maximum of 45 days. Sixty-one (59%) received preoperative RT/CRT., Results: In group A, flap failure occurred in four (4%) cases, and all were managed by PMMC. We encountered 22 (26%) fistulas and 14 (16%) stenoses. In group B, flap failure occurred in six (6%) cases and was managed by PMMC. We encountered seven (7%) fistulas and three (3%) stenoses. Comparing complications among the two groups, we encountered a statistically significant difference in favor of group B for both fistula (P < .001) and stenosis (P = .001). We did not evidence any significant difference in terms of flap success rate., Conclusions: First-line application of RF and ALT free flaps with long-lasting SBPS in reconstruction after PH/CH allows obtaining reduced incidences of both fistula and stenosis., Level of Evidence: 4. Laryngoscope, 127:2731-2737, 2017., (© 2017 The American Laryngological, Rhinological and Otological Society, Inc.)

gamma-Aminobutyric acid (GABA)(B) receptors are known to enhance activation of Kir3 channels generating G-protein-dependent inward rectifier K(+)-currents (GIRK). In some neurons, GABA(B) receptors either cause a tonic GIRK activation or generate a late K(+)-dependent inhibitory postsynaptic current component. However, other neurons express Kir2 channels, which generate a constitutive inward rectifier K(+)-current (CIRK) without requiring G-protein activation. The functional coupling of CIRK with GABA(B) receptors remained unexplored so far. About 50% of rat cerebellar granule cells in the internal granular layer of P19-26 rats showed a sizeable CIRK current. Here, we have investigated CIRK current regulation by GABA(B) receptors in cerebellar granule cells, which undergo GABAergic inhibition through Golgi cells. By using patch-clamp recording techniques and single-cell reverse transcriptase-polymerase chain reaction in acute cerebellar slices, we show that granule cells co-express Kir2 channels and GABA(B) receptors. CIRK current biophysical properties were compatible with Kir2 but not Kir3 channels, and could be inhibited by the GABA(B) receptor agonist baclofen. The action of baclofen was prevented by the GABA(B) receptor blocker CGP35348, involved a pertussis toxin-insensitive G-protein-mediated pathway, and required protein phosphatases inhibited by okadaic acid. GABA(B) receptor-dependent CIRK current inhibition could also be induced by repetitive GABAergic transmission at frequencies higher than the basal autorhythmic discharge of Golgi cells. These results suggest therefore that GABA(B) receptors can exert an inhibitory control over CIRK currents mediated by Kir2 channels. CIRK inhibition was associated with an increased input resistance around rest and caused a approximately 5 mV membrane depolarization. The pro-excitatory action of these effects at an inhibitory synapse may have an homeostatic role re-establishing granule cell readiness under conditions of strong inhibition.

Unlabelled: Whole-cell patch-clamp recordings in rat cerebellar slices were used to investigate the effect of metabotropic glutamate receptor activation on mossy fibre-granule cell synaptic transmission. Transient application of 20 microM 1S, 3R-aminocyclopentane-1, 3-dicarboxylic acid simultaneously with low-frequency NMDA receptor activation induced long-lasting non-decremental potentiation of both NMDA and non-NMDA receptor-mediated synaptic transmission. Potentiation could be prevented by application of the metabotropic glutamate receptor antagonist (+)-O-methyl-4-carboxyphenyl-glycine at 500 microM. Characteristically, NMDA potentiation was two to three times as large as non-NMDA current potentiation, occurred only in a slow subcomponent, and was voltage-independent. This result demonstrates a pivotal role of NMDA receptors in the metabotropic potentiation of transmission, which may be important in regulating cerebellar information processing., Keywords: cerebellum, LTP, metabotropic receptors, NMDA receptors, patch-clamp, rat

Decay kinetics of N-methyl-D-aspartate excitatory postsynaptic currents (NMDA-EPSCs) have been voltage-dependent in some, but not all neurons studied so far, and almost no information has been available on the voltage-dependence of the rising phase. In this work we investigated the effect of membrane potential on rising and decay kinetics of the NMDA-EPSC in cerebellar granule cells using the tight-seal whole-cell recording technique. NMDA-EPSCs were evoked by electrical mossy fibre stimulation in the presence of 10 microM 6-cyano-7-nitroquinoxaline-2,3-dione, 1.2 mM Mg2+ and 5 microM glycine. The rate of rise of NMDA-EPSCs remained substantially unchanged when the cell was depolarized, indicating that the limiting step of channel opening was voltage-insensitive. The NMDA-EPSC, however, flattened around the peak and the time-to-peak increased. This observation was explained by the influence of decay. Decay was biphasic and slowed down with membrane depolarization. Moreover, the fast component of decay increased less than the slow component. This complex voltage-dependence may extend the integrative role of the NMDA current during synaptic transmission.

Protein kinase C (PKC) is a Ca2+-dependent enzyme involved in synaptic transmission, which can be experimentally activated by the phorbol ester, phorbol 12-myristate-13-acetate (TPA). We studied the effects of TPA application on acetylcholine (ACh) release at the rat neuromuscular junction by means of the focal recording technique; possible effects of TPA at the postsynaptic site had been ruled out in preliminary studies. In extracellular solutions containing 2 mM Ca2+ and at the stimulation frequency of 0.1 Hz, TPA increased endplate current (EPC) amplitude. In non-stimulated preparations spontaneous current frequency was increased at a similar rate. The similar time course of TPA action on evoked and spontaneous currents suggests that an increased presynaptic Ca2+ efficacy can be considered to be the probable mechanism of action. The interactions of PKC with ACh release were further investigated. In 0.1 mM Ca2+ extracellular solutions, TPA enhanced evoked currents only at stimulation frequencies (e.g. 40 Hz) that were themselves capable of inducing facilitation. This facilitation is classically associated with presynaptic Ca2+ accumulation, indicating that PKC interacts synergistically with Ca2+ to facilitate ACh release. In particular, since mean quantum size and release probability remained almost unchanged during TPA facilitation, it was concluded that PKC acted by enlarging the immediately available store. Interestingly, TPA also increased the presynaptic currents that were observed to be largely brought about by Ca2+-dependent K+ currents: evidence was obtained to suggest that increases in these currents provide negative feedback against excess release activation rather than being an expression of enhanced Ca2+ influx.