Medicine and Health Sciences Commons^™

A Model Of The Effect Of Uncertainty On The C Elegans L2/L2d Decision, Leon Avery

Physiology and Biophysics Publications

Abstract

At the end of the first larval stage, the C elegans larva chooses between two developmental pathways, an L2 committed to reproductive development and an L2d, which has the option of undergoing reproductive development or entering the dauer diapause. I develop a quantitative model of this choice using mathematical tools developed for pricing financial options. The model predicts that the optimal decision must take into account not only the expected potential for reproductive growth, but also the uncertainty in that expected potential. Because the L2d has more flexibility than the L2, it is favored in unpredictable environments. I estimate …

Effect Of Enac Modulators On Rat Neural Responses To Nacl, Shobha Mummalaneni, Jie Qian, Tam-Hao T. Phan, Mee-Ra Rhyu, Gerard L. Heck, John A. Desimone, Vijay Lyall

Physiology and Biophysics Publications

The effects of small molecule ENaC activators N,N,N-trimethyl-2-((4-methyl-2-((4-methyl-1H-indol-3-yl)thio)pentanoyl)oxy)ethanaminiumiodide (Compound 1) and N-(2-hydroxyethyl)-4-methyl-2-((4-methyl-1H-indol-3-yl)thio)pentanamide(Compound 2), were tested on the benzamil (Bz)-sensitive NaCl chorda tympani (CT) taste nerve response under open-circuit conditions and under ±60 mV applied lingual voltage-clamp, and compared with the effects of known physiological activators (8-CPT-cAMP, BAPTA-AM, and alkaline pH), and an inhibitor (ionomycin+Ca2+) of ENaC. The NaCl CT response was enhanced at −60 mV and suppressed at +60 mV. In every case the CT response (r) versus voltage (V) curve was linear. All ENaC activators increased the open-circuit response (ro) and the voltage …

Selective Activation Of Htrpv1 By N-Geranyl Cyclopropylcarboxamide, An Amiloride-Insensitive Salt Taste Enhancer, Min Jung Kim, Hee Jin Son, Yiseul Kim, Hae-Jin Kweon, Byung-Chang Suh, Vijay Lyall, Mee-Ra Rhyu

Physiology and Biophysics Publications

TRPV1t, a variant of the transient receptor potential vanilloid-1 (TRPV1) has been proposed as a constitutively active, non-selective cation channel as a putative amiloride-insensitive salt taste receptor and shares many properties with TRPV1. Based on our previous chorda tympani taste nerve recordings in rodents and human sensory evaluations, we proposed that N-geranylcyclopropylcarboxamide (NGCC), a novel synthetic compound, acts as a salt taste enhancer by modulating the amiloride/benzamil-insensitive Na+ entry pathways. As an extension of this work, we investigated NGCC-induced human TRPV1 (hTRPV1) activation using a Ca2+-flux signaling assay in cultured cells. NGCC enhanced Ca2+ influx in hTRPV1-expressing cells in …

Lack Of Negatively Charged Residues At The External Mouth Of Kir2.2 Channels Enable The Voltage-Dependent Block By External Mg2+, Junwei Li, Xiaoxiao Xie, Jun Liu, Hui Yu, Suhua Zhang, Yong Zhan, Hailin Zhang, Diomedes E. Logothetis, Hailong An

Physiology and Biophysics Publications

Kir channels display voltage-dependent block by cytosolic cations such as Mg2+ and polyamines that causes inward rectification. In fact, cations can regulate K channel activity from both the extracellular and intracellular sides. Previous studies have provided insight into the up-regulation of Kir channel activity by extracellular K+ concentration. In contrast, extracellular Mg2+ has been found to reduce the amplitude of the single-channel current at milimolar concentrations. However, little is known about the molecular mechanism of Kir channel blockade by external Mg2+ and the relationship between the Mg2+ blockade and activity potentiation by permeant K+ ions. In this study, we applied …

Suppression Of The Pi3k Pathway In Vivo Reduces Cystitis-Induced Bladder Hypertrophy And Restores Bladder Capacity Examined By Magnetic Resonance Imaging, Zhongwei Qiao, Chunmei Xia, Shanwei Shen, Frank D. Corwin, Miao Liu, Ruijuan Guan, John R. Grider, Li-Ya Qiao

Physiology and Biophysics Publications

This study utilized magnetic resonance imaging (MRI) to monitor the real-time status of the urinary bladder in normal and diseased states following cyclophosphamide (CYP)-induced cystitis, and also examined the role of the phosphoinositide 3-kinase (PI3K) pathway in the regulation of urinary bladder hypertrophy in vivo. Our results showed that under MRI visualization the urinary bladder wall was significantly thickened at 8 h and 48 h post CYP injection. The intravesical volume of the urinary bladder was also markedly reduced. Treatment of the cystitis animals with a specific PI3K inhibitor LY294002 reduced cystitis-induced bladder wall thickening and enlarged the intravesical volumes. …