Robert D. Grubbs

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The development of new techniques for measuring intracellular free Mg2+ during the 1980s has provided investigators with the tools needed to produce new insights into the regulation of cellular magnesium. Within the limits of this technology, it appears that all mammalian cells maintain free cytosolic Mg2+ levels within the fairly narrow range of 0.25–1 mM.(More)
Of the two major intracellular divalent cations, Ca2+ has been studied much more extensively than Mg2+ and is now well accepted as a major intracellular regulator. This review focuses instead on some recent advances in the understanding of the physiology and biochemistry of Mg2+. For purposes of discussion, four criteria have been developed that should be(More)
The development of fluorescent ion-selective indicators for magnesium has provided valuable tools for measuring second-by-second changes in cytosolic magnesium activity. In the course of establishing appropriate protocols for using one of these indicators, mag-fura-2, to measure magnesium activity in BC3H-1 cells and chick ventricular myocytes, many(More)
Endocytosis of agonist-activated G protein-coupled receptors (GPCRs) is required for both resensitization and recycling to the cell surface as well as lysosomal degradation. Thus, this process is crucial for regulation of receptor signaling and cellular responsiveness. Although many GPCRs internalize into clathrin-coated vesicles in a dynamin-dependent(More)
To characterize the Mg2+ buffering of cultured chick ventricular myocytes, cytosolic Mg2+ was increased by liberating Mg2+ normally chelated by ATP upon total depletion of ATP content. Because the total Mg content and cell volume remained constant during this time, the difference between the amount of Mg2+ liberated (2.7 mM) and the 0.9 mM increase in(More)
Age and growth estimates were determined for the sandbar shark, Carcharhinus plumbeus, from Oahu, Hawaii in the central Pacific Ocean. Age estimates were obtained through vertebral centra analysis of 187 sharks. We verified our age estimates through marginal increment analysis of centra and oxytetracycline marking methods of at liberty sandbar sharks. Sizes(More)
The murine S49 lymphoma cell transports Mg2+ by a system distinct from systems responsible for Ca2+ influx (J. Physiol. London 337: 351-371, 1983). We have now determined the ability of various cations, anions, and drugs to modulate Mg2+ influx. Neither sulfate, nitrate, phosphate, nor bicarbonate altered Mg2+ influx. Among cations only T1+, Ba2+, Zn2+,(More)
The magnesium buffer coefficient (B Mg) was calculated for BC3H-1 cells from the rise in cytosolic Mg2+ activity observed when magnesium was released from ATP after iodoacetate (IAA) and NaCN treatment. The basal cytosolic Mg2+ activity (0.54±0.1 mM) measured with mag-fura-2 doubled when 4.54 mM magnesium was liberated from ATP:B Mg was 12.9 indicating that(More)
The organophosphorus agent sarin is a potent inhibitor of acetylcholinesterase. Experiments tested the influence of exposure to low doses of sarin along with psychological stress on delayed behavioral and endocrine changes in mice. Motor activity, acoustic startle response (ASR), pre-pulse inhibition (PPI) of ASR, activity of cholinesterase in blood and(More)
Intracellular pH (pHi) was studied in the smooth muscle-like cell line, BC3H-1, using the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5,6-carboxyfluorescein (BCECF). The initial pHi measured in 20 mM Na N-2-hydroxyethylpiperazine-N'-2 ethanesulfonic acid-buffered medium [NHB; external pH (pHo) 7.4, 37 degrees C] was 6.89 +/- 0.01 (n = 178). pHi(More)