scholarly journals Properties of the pH-sensitive site that controls the lambda max of Limulus metarhodopsin.

1981 ◽  
Vol 77 (2) ◽  
pp. 191-203 ◽  
Author(s):  
J E Lisman ◽  
S Schulman ◽  
Y Sheline ◽  
P K Brown
Keyword(s):  
Intracellular Ph ◽  
Receptor Potential ◽  
Ph Sensitive ◽  
Phenol Red ◽  
Intracellular Recordings ◽  
Ph Buffering ◽  
Intracellular Injection ◽  
Early Receptor Potential ◽  
Sensitive Site ◽  
Secondary Result

A pH-sensitive site controls the lambda max of Limulus metarhodopsin. The properties of this site were examined using intracellular recordings of the early receptor potential (ERP) as a pigment assay. ERPs recorded over a range of extracellular pHs indicate that the apparent pK of the site is in the range of 8.3-8.6. Several lines of evidence indicate that the site responds directly to changes in extracellular pH (pHo) rather than to changes in intracellular pH(pHi) that follow as a secondary result of changing pHo : (a) the effect of changing pHo was rapid (less than 60 s); (b) when pHo was raised, the simultaneous rise in pHi, as measured with phenol red, was relatively small; (c) raising pHi by intracellular injection of pH 10 glycine buffer did not affect the site; and (d) the effect of changing pH0 could not be blocked by increasing the intracellular pH buffering capacity. It is concluded that the pH-sensitive site on metarhodopsin is on the extracellular surface of the plasma membrane.

scholarly journals Fast electrical potentials arising from activation of metarhodopsin in the fly.

1980 ◽  
Vol 75 (4) ◽  
pp. 381-402 ◽  
Author(s):  
B Minke ◽  
K Kirschfeld
Keyword(s):  
Light Intensity ◽  
Receptor Potential ◽  
Second Order ◽  
Intracellular Recordings ◽  
M1 Phase ◽  
Cellular Origin ◽  
Electrical Potentials ◽  
Early Receptor Potential ◽  
Order Neuron

The cellular origin and properties of fast electrical potentials arising from activation of Calliphora photopigment were investigated. It was found by intracellular recordings that only the corneal-negative M1 phase of fly M potential arises in the photoreceptors' membrane. This M1 phase has all the accepted characteristics of an early receptor potential (ERP). It has no detectable latency, it survives fixation with glutaraldehyde, it is linear with light intensity below pigment saturation, and it is linear with the amount of metarhodopsin activated by light. The Calliphora ERP was found, however, to be exceptional because activation of rhodopsin, which causes the formation of metarhodopsin in 125 microsecond (25 degrees C), was not manifested in the ERP. Also, the extracellularly recorded ERP was not proportional to the rate of photopigment conversion. The corneal-positive M2 phase of the M potential was found to arise from second-order lamina neurons (L neurons). Intracellular recordings from these cells showed a fast hyperpolarizing potential, which preceded the normal hyperpolarizing transient of these cells. This fast potential appeared only when metarhodopsin was activated by a strong flash. The data indicate that the intracellularly recorded positive ERP, which arises from activation of metarhodoposin, elicits a hyperpolarizing fast potential in the second-order neuron. This potential is most likely the source of the corneal-positive M potential.

LONG TERM EFFECTS OF THYROID STIMULATING HORMONE AND INSULIN ON INTRACELLULAR pH IN FRTL-5 CELLS

1992 ◽  
Vol 133 (2) ◽  
pp. R9-R11
Author(s):  
A.M. Wood ◽  
S.P. Bidey ◽  
J. Soden ◽  
W.R. Robertson
Keyword(s):  
Intracellular Ph ◽  
Small Groups ◽  
Thyroid Stimulating Hormone ◽  
Ph Sensitive ◽  
Long Term Effects ◽  
Bicarbonate Ions ◽  
Chronic Effects ◽  
Petri Dishes ◽  
Presence And Absence

ABSTRACT We have studied the chronic effects of TSH (100μU/ml) and insulin (10μg/ml) on intracellular pH (pHi) in FRTL-5 cells using the pH sensitive probe 2′7-bis (2-carboxyethyl-5′-6′) carboxyfluorescein. FRTL-5 cells were cultured on Petri dishes either in the presence of 4H, ie. Coons F-12 containing cortisol (10nM), transferrin (0.5μg/ml), glycyl-histidyl lysine acetate (10ng/ml) and somatostatin (10μg/ml), or with 4H+insulin (5H), 4H+TSH, or 4H+TSH+insulin (6H). pHi was measured in small groups of cells by microspectrofluorimetry both in the presence and absence of bicarbonate ions after cells had been deprived of serum for at least a day. In

Intracellular pH-Sensitive PEG-block-Acetalated-Dextrans as Efficient Drug Delivery Platforms

2013 ◽  
Vol 5 (21) ◽  
pp. 10760-10766 ◽  
Author(s):  
Zhe Zhang ◽  
Xiaofei Chen ◽  
Li Chen ◽  
Shuangjiang Yu ◽  
Yue Cao ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Intracellular Ph ◽  
Ph Sensitive

Design and validation of a new ratiometric intracellular pH imaging probe using lanthanide-doped upconverting nanoparticles

2017 ◽  
Vol 46 (40) ◽  
pp. 13957-13965 ◽  
Author(s):  
Shuoren Du ◽  
Javier Hernández-Gil ◽  
Hao Dong ◽  
Xiaoyu Zheng ◽  
Guangming Lyu ◽  
...  
Keyword(s):  
Intracellular Ph ◽  
Quantitative Imaging ◽  
Living Cells ◽  
Ph Sensitive ◽  
Upconversion Nanoparticles ◽  
Imaging Probe ◽  
Ph Imaging ◽  
Ratiometric Probe ◽  
Subcellular Level

A ratiometric probe based on upconversion nanoparticles modified with a pH sensitive moiety for the quantitative imaging of pH at the subcellular level in living cells.

scholarly journals Electrophysiological measurement of the number of rhodopsin molecules in single Limulus photoreceptors.

1977 ◽  
Vol 70 (5) ◽  
pp. 621-633 ◽  
Author(s):  
J E Lisman ◽  
H Bering
Keyword(s):  
Relative Intensity ◽  
Surface Density ◽  
Receptor Potential ◽  
Absolute Intensity ◽  
Charge Movement ◽  
Half Time ◽  
Quantal Response ◽  
Early Receptor Potential ◽  
Electrophysiological Measurement ◽  
Electrophysiological Methods

Two partly independent electrophysiological methods are described for measuring the number of rhodopsin molecules (R) in single ventral photoreceptors. Method 1 is based on measurements of the relative intensity required to elicit a quantal response and the relative intensity required to half-saturate the early receptor potential (ERP). Method 2 is based on measurements of the absolute intensity required to elicit a quantal response. Both methods give values of R approximately equal to 10(9). From these and other measurements, estimates are derived for the surface density of rhodopsin (8,000/micrometer2), the charge movement during the ERP per isomerized rhodopsin (20 X 10(-21) C), and the half-time for thermal isomerization of rhodopsin (36yr).

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