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PubMed1992

Platelet and erythrocyte Mg2+, Ca2+, Na+, K+ and cell membrane adenosine triphosphatase activity in essential hypertension in blacks.

OBJECTIVE: To assess the relationship between intracellular Mg2+, Ca2+, Na+ and K+ and cell membrane adenosine triphosphatase (ATPase) activity in normotensive and hypertensive blacks. DESIGN: Intracellular cations and cell membrane ATPase activity were studied in black patients with untreated essential hypertension and age-, weight- and height-matched normotensive controls. Platelet, erythrocyte and serum Mg2+, Ca2+, Na+ and K+ levels as well as platelet and erythrocyte membrane Na+,K(+)-ATPase, Ca(2+)-ATPase and Mg(2+)-ATPase activities were measured in all subjects. METHODS: Intracellular Na+ and K+ were measured by flame photometry and Mg+ and Ca+ by atomic absorption spectrophotometry. Cell membrane ATPase activity was determined by a colorimetric method. RESULTS: The hypertensive group consistently demonstrated depressed activity of each ATPase studied, with significantly lower serum Mg2+, serum K+, erythrocyte Mg2+ and platelet Mg2+ levels compared with the normotensive group. Platelet Na+ and Ca2+ and erythrocyte Ca2+ were significantly elevated in the hypertensive group. In the hypertensive group, mean arterial pressure (MAP) was inversely correlated with platelet and erythrocyte membrane Na+,K(+)-ATPase, Ca(2+)-ATPase and Mg(2+)-ATPase. Serum Mg2+, serum Ca2+ and platelet Mg2+ were negatively correlated with MAP in the hypertensive group whilst erythrocyte and platelet Ca2+ were positively correlated. In the normotensive group, platelet Mg2+ and MAP were negatively, and erythrocyte Ca2+ and MAP, positively correlated. CONCLUSIONS: Black patients with essential hypertension have widespread depression of cell membrane Na+,K(+)-ATPase, Ca(2+)-ATPase and Mg(2+)-ATPase activities with serum and intracellular Mg2+ depletion and cytosolic Na+ and Ca2+ overload, which may reflect an underlying membrane abnormality in essential hypertension. These cellular abnormalities may be related to the defective transport mechanisms that in turn may be aggravated by Mg2+ depletion.

Black People↗

PubMed1993

Acute effects of alcohol ingestion on blood pressure and erythrocyte sodium concentration.

OBJECTIVE: To examine the acute effects of alcohol on blood pressure and erythrocyte cation concentrations in patients with essential hypertension. DESIGN: An alcoholic drink or an isocaloric control drink was given during supper in random order on different days, and blood pressure and erythrocyte cation concentrations were measured before and 2 h after the meal. METHODS: The subjects were 21 men with essential hypertension who habitually drank alcohol. Blood pressure was measured with a semi-automated sphygmomanometer, and erythrocyte cation concentrations were measured by flame photometry after haemolysis with distilled water. RESULTS: Blood pressure decreased after both drinks, but the decrease was significantly larger after the alcoholic drink than after the control drink. There was a significant difference between the changes in erythrocyte sodium caused by the alcoholic and the control drink. Furthermore, there were significant positive correlations between the fall in blood pressures and the decrease in erythrocyte sodium concentration. CONCLUSION: The predominant acute effect of alcohol ingestion in patients with hypertension is blood pressure reduction, and it may be associated with a decrease in intracellular sodium.

Adult↗

PubMed1995

Alterations in intracellular cations and cell membrane ATPase activity in patients with malignant hypertension.

OBJECTIVE: To determine whether cellular cation concentrations and cell membrane ATPase activity are altered in patients with malignant hypertension. DESIGN: Sixteen black patients with malignant hypertension were studied and compared with age- and sex-matched essential hypertensive and normotensive subjects. Calcium, magnesium, sodium and potassium concentrations and cell membrane Na,K-ATPase, Ca-ATPase and Mg-ATPase activities were determined in platelets and erythrocytes. METHODS: Intracellular concentrations of total magnesium and calcium were measured by atomic absorption spectrophotometry, and those of sodium and potassium by flame photometry. Cell membrane ATPase activity was measured by a colorimetric method. RESULTS: The intracellular calcium level was significantly elevated and intracellular magnesium and potassium levels and cell membrane ATPase activity significantly decreased in the hypertensive group. These changes were more marked in patients with malignant hypertension than in patients with benign essential hypertension. In the malignant hypertensive group, mean arterial pressure was negatively correlated with intracellular magnesium and positively correlated with intracellular calcium and sodium levels. CONCLUSIONS: Cellular cation changes in malignant hypertension may be related to altered transmembrane transport mechanisms and activation of the renin-angiotensin system. These alterations may be more pronounced in the malignant than in the benign phase of hypertension.

Adenosine Triphosphatases↗

PubMed1990

Transport of water and electrolytes by rotavirus-infected mouse intestine: a time course study.

The movement of water and transport of Na+ and Cl- by mid-small intestine (M-SI) of rotavirus-infected neonatal mice was investigated by an in vitro perfusion technique. The concentrations of Na+, K+, and Cl- in the luminal contents of upper, middle, and lower small intestine and colon of infected mice were determined by flame photometry (Na+, K+) and an ion selective microelectrode (Cl-). In M-SI, maximal disturbance of water transport occurred at 72 h postinfection (PI): Infected tissue exhibited net water secretion. Water transport was also impaired at 144 h PI. Net secretion of Cl- occurred at 72 h PI, with some evidence of a second phase of reduced magnitude at 120-144 h PI. The magnitude and statistical significance of changes in Na+ transport were both less than those for Cl-, but the pattern of change was similar to that for Cl-. Luminal concentrations of Na+ were elevated between 48 and 144 h PI in the small intestine; this was particularly so in distal regions. Luminal Cl- concentration was maximally elevated to a considerable degree at 72 h PI and remained high at 96 h PI throughout the small intestine; thereafter, Cl- concentration returned to near normal. K+ concentration was unchanged in the small intestinal lumen; in the colon, however, K+ concentrations were depressed 72-168 h PI. In the light of previous data from this laboratory, the present data are interpreted as evidence for a secretory component in rotavirus-induced diarrhea.

Animals↗

PubMed1998

Nasal ciliary beat frequency is age independent.

OBJECTIVES: Evaluate the age-dependency of ciliary beat frequency (CBF) in biopsies after ciliogenesis in culture. STUDY DESIGN: Retrospective analysis of CBF and ciliary ultrastructure in biopsies and after ciliogenesis from 203 individuals, aged 3 months to 74 years. METHODS: All patients with successful culture were included. Ciliogenesis was obtained using the sequential monolayer-suspension culture technique for dissociated nasal epithelial cells. CBF was measured using computerized microscope photometry. Secondary ultrastructural abnormalities were evaluated in transmission electron microscopy. RESULTS: There was no correlation between age and CBF, in either the biopsies (7.0 +/- 2.6 Hz; n = 113) or after ciliogenesis in culture (8.1 +/- 1.3 Hz; n = 203). Even in individuals older than 70 years, CBF was normal in bioptic material (6.7 +/- 1.7 Hz) and after ciliogenesis in culture (7.9 +/- 1.0 Hz). Also, in individuals less than 1 year of age CBF was normal in biopsies as well as after ciliogenesis. CBF correlated inversely with the percentage of secondary ultrastructural abnormalities in the biopsies as seen with transmission electron microscopy: 8.1 +/- 1.8 Hz when ciliary ultrastructure was normal and 3.5 +/- 3.3 Hz in cases of severe secondary ciliary dyskinesia. After ciliogenesis in culture, ciliary ultrastructure was always normal, as was CBF. CONCLUSION: CBF is age independent but correlates with secondary ultrastructural abnormalities. CBF after ciliogenesis in culture is the intrinsic one.

Adolescent↗

PubMed1990

Effect of atrial natriuretic peptide on ischemic brain edema: changes in brain water and electrolytes.

The effects of intraventricularly administered atrial natriuretic peptide (ANP) on the brain water, sodium, and potassium contents in ischemic brain edema were investigated. By use of a three-vessel occlusion model, ischemic brain edema was produced in the rat brain by 15 minutes of global ischemia followed by recirculation. Water content was measured by means of a drying/weighing method; sodium and potassium contents were measured by means of flame photometry. The effects of intraventricular administration of ANP were evaluated by a comparison between the groups given 2 and 5 micrograms of atriopeptin II (treated) and those given 0.9% NaCl (sham-treated). The treated groups showed significant decreases in brain water (P less than 0.02) and sodium (P less than 0.01) contents at 15 and 30 minutes after recirculation, whereas the brain potassium contents remained unaltered. Before ischemia and immediately after 15 minutes of ischemia, intraventricularly administered ANP did not significantly change the brain water, sodium, or potassium contents. There was no significant difference in the effect on the amount of brain water and sodium between the two doses (2 and 5 micrograms). These effects of ANP were thought not to be mediated by primary changes in serum osmolality and sodium and potassium concentrations, because intraventricular administration of ANP did not change them significantly. The present results reveal that, in ischemic brain edema, ANP may act directly on the central nervous system to inhibit brain water and sodium accumulation.

Animals↗

PubMed1998

Intraoperative detection of malignant gliomas by 5-aminolevulinic acid-induced porphyrin fluorescence.

OBJECTIVE: Survival after surgery and radiotherapy for the treatment of malignant gliomas is linked to the completeness of tumor removal. Therefore, methods that permit intraoperative identification of residual tumor tissue may be of benefit. In a preliminary investigation, we have studied the value of fluorescent porphyrins that accumulate in malignant tissue after administration of a precursor (5-aminolevulinic acid) for labeling of malignant gliomas in nine patients. METHODS: Three hours before the induction of anesthesia, 10 mg 5-aminolevulinic acid/kg body weight was administered orally. Intraoperatively, red porphyrin fluorescence was observed with a 455-nm long-pass filter after excitation with violet-blue (375-440 nm) xenon light and was verified by analysis of fluorescence spectra. Fluorescing and nonfluorescing samples taken from the tumor perimeters were examined histologically or used to study the photobleaching of porphyrins by excitation light and white light from the operating microscope. Plasma and erythrocyte porphyrin levels were determined by fluorescence photometry. RESULTS: Normal brain tissue revealed no porphyrin fluorescence, whereas tumor tissue was distinguished by bright red fluorescence. For a total of 89 tissue biopsies, sensitivity was 85% and specificity was 100% for the detection of malignant tissue. For seven of nine patients, visible porphyrin fluorescence led to further resection of the tumor. Under operating light conditions, fluorescence decayed to 36% in 25 minutes for violet-blue light and in 87 minutes for white light. Plasma and erythrocyte porphyrin contents increased slightly, without exceeding normal levels. CONCLUSION: Our observations suggest that 5-aminolevulinic acid-induced porphyrin fluorescence may label malignant gliomas safely and accurately enough to enhance the completeness of tumor removal.

Aged↗

PubMed1980

The absence of the Ives effect in a deuteranope.

Ives found that when monochromatic stimuli are matched to white by flicker photometry, they are not equal in brightness to the white by direct comparison, and the discrepancy is minimal for yellow but is increased for longer and shorter wavelengths. On the two sides of yellow, the colors are more saturated, and Ives postulated that brightness involves the sum of a chromatic component and an achromatic component and that the chromatic component varies with the saturation. In the case of a deuteranope, one would expect a vigorous chromatic response for yellow and blue stimuli but a poor response for the neutral part of the spectrum. The Ives effect is virtually nonexistent for subject SR, who is a deuteranope. In terms of the zone theory of color vision, this would mean that the blue-yellow chromatic channel contributes little or nothing to brightness. In a normal observer, the blue-yellow mechanism can be isolated by using blues and yellows depurified with white, but in this case the Ives effect is found to exist.

Adult↗

PubMed1990

Effects of dioptric blur on the Vistech contrast sensitivity test.

We studied the effect of dioptric blur on contrast sensitivity using the Vistech Vision Contrast System Chart. One diopter of blur affected the Vistech gratings by an amount consistent with expectations; sensitivity loss was greatest with higher spatial frequencies. However, a second diopter of blur induced an equal sensitivity loss for all spatial frequencies. A third diopter induced the greatest loss at the lowest frequency and an actual increase in sensitivity at the highest frequencies. This surprising finding is due to an interaction between "spuriously resolved" gratings and the border of the grating disc which resulted in the finest grating discs appearing to contain low frequency borders aligned with the fine gratings. Actually the fine gratings in the disc were invisible. When performing scanning photometry on the Vistech chart, we found that the contrasts of the unblurred gratings with higher contrast levels are 2.7 to 5.4 times higher than those stated by the manufacturer. The presence of this aliasing artifact indicates that the Vistech Vision Contrast System may produce erroneous results when used under conditions of high dioptric blur.

Adult↗

PubMed1997

A longitudinal study of visual evoked responses to tritan stimuli in human infants.

The principal goal of this study was to assess the development of the S-cone pathway in human infants. For comparison, development of the L-M opponent pathway was also assessed. Visual evoked responses were measured to chromatic (tritan and red-green) and luminance-modulated (yellow-black) sinusoidal gratings of 0.2 cpd, viewed binocularly at a distance of 40 cm. For each type of chromatic stimulus, responses were recorded at a range of color ratios around the adult isoluminant point, as determined using standard flicker photometry criteria. Presentation was by abrupt pattern-onset with a stimulus duration of 100 ms and an interstimulus interval of 400 ms. Responses were recorded from Oz, referred to Cz, by averaging 30 sweeps. Infants were examined between the ages of 4 weeks and 3 months. Reliable visual evoked responses were recorded to isoluminant tritan stimuli from as early as 4 weeks of age, and to red-green stimuli from 6 weeks. Responses to the luminance-modulated stimuli were evident in all infants at 4 weeks of age (the earliest age examined). Our results provide evidence that the rate of development for pathways mediating information about tritan stimuli, red-green stimuli, and luminance-modulated stimuli is similar.

Aging↗

PubMed1989

Normotension with decreased plasma renin activity and low serum ionic calcium levels: a prehypertensive state?

We studied the relationships between the renin-angiotensin-aldosterone system and calcium and magnesium levels in both serum and urine in 51 volunteer normotensive subjects, divided into two groups. Group 1 was made up of the 25 subjects whose levels of plasma renin activity were the lowest (1.93 +/- 0.70 ng/ml/hr). Group 2 comprised the 26 subjects with the highest plasma renin activity levels (4.80 +/- 0.84 ng/ml/hr). The following parameters were measured on all subjects: plasma renin activity and plasma and urinary aldosterone levels (by radioimmunoassay), serum ionic calcium levels (by Nova-2), total serum calcium, and serum and urinary magnesium values (by atomic absorption), serum and urinary sodium and potassium levels (by flame photometry), and creatinine clearance. In the group with low plasma renin activity (group 1), our findings included low serum ionic calcium levels (P less than .001); high coefficients of plasma aldosterone/plasma renin activity and urinary aldosterone/plasma renin activity (P less than .001); a significant correlation between the serum ionic calcium level and plasma renin activity (P less than .001); and an inverse correlation between systolic arterial tension and the serum ionic calcium level (P less than .05). These changes were more similar to change described in hypertensive patients with low plasma renin activity than to the findings in group 2 subjects. We speculate that normotensive subjects with low plasma renin activity present significant changes in the relationship between the renin-angiotensin-aldosterone system and sodium and calcium levels, and that this group is at risk for hypertension. A diet low in sodium and high in calcium could be an effective preventive measure.

Adult↗

PubMed1986

Clinical evaluation of a dry chemistry strip theophylline assay.

In this dry chemistry strip immunoassay, flavin adenine dinucleotide (FAD) conjugated theophylline competes with theophylline in the sample for binding to a specific monoclonal antibody. Unbound conjugate can then activate apoglucose oxidase, the activity of which is coupled to a peroxidase chromogenic reaction that allows kinetic monitoring by reflectance photometry. Thirty microliters of diluted sample is placed onto the reagent pad. The strip is inserted into the analyzer, and a digital readout appears 80 s later. Within-run precision was 4.5% based on patient duplicates. Between-day precision was 7.6% at 10 mg/L (n = 29) and 4.5% at 20 mg/L (n = 27). The assay was linear to at least 35 mg/L. There was good agreement between the test method and fluorescence polarization immunoassay: y (test) = -0.2865 + 1.085x (reference), n = 79, r = 0.980, Syx = 1.64. The assay showed good specificity except in patients receiving dimenhydrinate or suffering from renal failure. This system of assay provides reliable measurement of theophylline and will allow easy accessibility to this measurement for physicians working in emergency departments or private offices.

Adult↗

PubMed2004

Analytic evaluation and application of a novel spectrophotometric serum lithium method to a rapid response laboratory.

The authors present an evaluation of the Lithium DST spectrophotometric method developed by Thermotrace (Victoria, Australia) on a Hitachi 917 analyzer. Accuracy was assessed by method comparison with an ion-selective electrode (ISE; Roche Integra 700) (n = 80). Linearity, within-run and between-run precision, and susceptibility to interference by hemolysis, icterus, lipemia, and sodium were assessed. The method was linear to 3.0 mM/L, and analyzer auto-dilution extended the reportable range to 7.2 mmol/L. Within-run coefficient of variation was 1.5% at 0.68 mmol/L and 0.7% at 2.06 mM/L. Between-run precision for the same lithium concentrations assayed daily for 20 days were 3.1% and 1.9%, respectively. Method agreement with ISE was excellent, with an intercept of 0.000 and slope of 1.000 by Passing Bablock regression analysis. Hemolysis, icterus, lipemia, and high and low sodium levels did not significantly interfere. The manufacturer's recommended calibration stability of 1 week was confirmed. The authors conclude that this method is reliable, accurate, and precise. The Thermotrace serum lithium spectrophotometric method provides a useful alternative to ISE or flame photometry, facilitates workstation consolidation on the Hitachi 917 multiple-channel analyzer, and is well adapted for use in a rapid response laboratory.

Antimanic Agents↗

PubMed2003

Variation in urine composition in the human urinary tract: evidence of urothelial function in situ?

PURPOSE: An increased awareness of the concept that the urothelium has a significant transport function led us to question whether urine composition changes as it passes along the human lower urinary tract. MATERIALS AND METHODS: Urine samples from the bladder and renal pelvis were collected from 30 adults who underwent percutaneous nephrolithotomy (27) or ureteral stent insertion before lithotripsy (3). Urine was obtained from the 2 renal pelves (operative and contralateral sides) in 6 patients (24%). Urine pH was measured using an ultra-thin glass pH electrode. Urinary osmolality, Na and K were measured by micro-osmometry and flame photometry, respectively. Comparison of data sets was achieved using conventional nonparametric statistical methods. RESULTS: Median bladder urine pH in 30 patients, osmolality in 16, Na in 16 and K in 15 were significantly higher than in the renal pelvis at 6.76 (IQR 6.23 to 6.99), 469 mOsm. kg.1 (IQR 349 to 553), 132 (IQR 100 to 154) and 45 mM. (IQR 30 to 64) versus 6.08 (IQR 5.84 to 6.89), 308 mOsm. kg.1 (IQR 248 to 465), 90 (IQR 69 to 115) and 17 mM. (IQR 10 to 47), respectively (p < or = 0.05). There was no significant difference in these parameters in the urine of the paired renal pelves. CONCLUSIONS: Bladder urine pH, osmolality, Na and K significantly differ from values in the renal pelvis in moderately hydrated humans. Our data show that urine composition is modified in the lower urinary tract, supporting the concept of a dynamic urothelium. We propose that urothelial-urinary interactions and urinalysis need reappraisal, particularly in investigations of urinary stone formation and sensory bladder function.

Adult↗

PubMed2006

Compensation for light loss resulting from filtering by macular pigment: relation to the S-cone pathway.

PURPOSE: Macular pigment (MP) filters short-wavelength light before it reaches the visual pigments. At peak absorbance (460 nm), transmission of light through MP can range from almost 100% transmission to as little as 3%. As a result of the uneven topographic distribution of MP, spatial nonuniformities in visual perception would result if the visual system did not compensate for filtering differences across the central retina. This study characterizes compensation for different densities of MP. METHODS: Sixteen young subjects (aged 24-40 years) with a wide range of MP density were studied. Increment thresholds were measured at 440 and 500 nm in the center of the fovea and at 6 degrees to 7 degrees eccentricity using conditions chosen to isolate the pi-1 mechanism. For six of the subjects, increment thresholds were also obtained for eccentricities of 1 degrees , 1.75 degrees , and 3 degrees . MP density was measured using heterochromatic flicker photometry at the same locations as the increment thresholds. RESULTS: Peak sensitivity of the short-wavelength pathway across the central retina was constant despite MP density differences as large as 1.0 log unit. CONCLUSIONS: These results suggest that the visual system increases gain of the S-cone pathway to offset light absorption by MP.

Adaptation, Ocular↗

PubMed1986

Occurrence of ploidy shift in a strain of the imperfect yeast Candida albicans.

A clinical isolate of Candida albicans, a member of the Fungi Imperfecti, was polyploid as shown by the fact that it contained two kinds of nuclei, one of diploid and one of tetraploid DNA content. These determinations were made by fluorescence microscopy-photometry. The nucleus-associated organelles (NAOs), or spindle pole bodies, of yeast cells in this isolate were classified into two groups, one diploid and the other tetraploid, according to their dimensions as determined by serial thin-sectioning electron microscopy. A ploidy shift from diploid to tetraploid was found in individual cells of a culture of this isolate undergoing diphasic growth in minimal salts medium. A process of shift-down or reduction of ploidy from tetraploid to diploid was also observed by electron microscopy during these growth conditions: this appeared to occur in large cells which showed multiple spindle formation during nuclear division, a phenomenon apparently similar to the process of meiosis II during sporogenesis of Saccharomyces cerevisiae, but differing in that it produces diploid daughter nuclei by the vegetative process.

Candida albicans↗

PubMed2000

Protonmotive force regulates the membrane conductance of Streptococcus bovis in a non-ohmic fashion.

Because the DCCD (dicyclohexylcarbodiimide)-sensitive, F-ATPase-mediated, futile ATP hydrolysis of non-growing Streptococcus bovis JB1 cells was not affected by sodium or potassium, ATP hydrolysis appeared to be dependent only upon the rate of proton flux across the cell membrane. However, available estimates of bacterial proton conductance were too low to account for the rate of ATP turnover observed in S. bovis. When de-energized cells were subjected to large pH gradients (2.75 units, or -170 mV), internal pH declined at a rate of 0.15 pH units s(-1). Based on an estimated cellular buffering capacity of 200 nmol H+ (mg protein)(-1) per pH unit, H+ flux across the cell membrane (at -170 mV) was 108 mmol (g protein)(-1) h(-1). When potassium-loaded cells were treated with valinomycin in low-potassium buffers, initial K+ efflux generated membrane potentials in close agreement with values predicted by the Nernst equation. These artificial membrane potentials drove H+ uptake, and H+ influx was counterbalanced by a further loss of cellular K+. Flame photometry indicated that the rate of K+ loss was 215 (+/-26) mmol K+ (g protein)(-1) h(-1) at -170 mV, but the potassium-sensitive fluorescent compound CD222 indicated that this rate was only 110 (+/-44) mmol K+ (g protein)(-1) h(-1). As pH gradients or membrane potentials were reduced, the rate of H+ flux declined in a non-ohmic fashion, and all rates were <25 mmol (g protein)(-1) h(-1) at a driving force of -80 mV. Previous estimates of bacterial proton flux were based on low and unphysiological protonmotive forces, and the assumption that H+ influx rate would be ohmic. Rates of H+ influx into S. bovis cells [as high as 9x10(-11) mol H+ (cm membrane)(-2) s(-1)] were similar to rates reported for respiring mitochondria, but were at least 20-fold greater than any rate previously reported in lactic acid bacteria.

Adenosine Triphosphatases↗

PubMed2000

Calcium-mediated signaling during sandalwood somatic embryogenesis. Role for exogenous calcium as second messenger.

The possible involvement of Ca(2+)-mediated signaling in the induction/regulation of somatic embryogenesis from pro-embryogenic cells of sandalwood (Santalum album) has been investigated. (45)Ca(2+)-uptake studies and fura-2 fluorescence ratio photometry were used to measure changes in [Ca(2+)](cyt) of pro-embryogenic cells in response to culture conditions conducive for embryo development. Sandalwood pro-embryogenic cell masses (PEMs) are obtained in the callus proliferation medium that contains the auxin 2,4-dichlorophenoxyacetic acid. Subculture of PEMs into the embryo differentiation medium, which lacks 2,4-dichlorophenoxyacetic acid and has higher osmoticum, results in a 4-fold higher (45)Ca(2+) incorporation into the symplast. Fura-2 ratiometric analysis corroboratively shows a 10- to 16-fold increase in the [Ca(2+)](cyt) of PEMs, increasing from a resting concentration of 30 to 50 nM to 650 to 800 nM. Chelation of exogenous Ca(2+) with ethyleneglycol-bis(aminoethyl ether)-N,N'-tetraacetic acid arrests such an elevation in [Ca(2+)](cyt). Exogenous Ca(2+) when chelated or deprived also arrests embryo development and inhibits the accumulation of a sandalwood Ca(2+)-dependent protein kinase. However, such culture conditions do not cause cell death as the PEMs continue to proliferate to form larger cell clumps. Culture treatment with N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide reduced embryogenic frequency by 85%, indicating that blockage of Ca(2+)-mediated signaling pathway(s) involving sandalwood Ca(2+)-dependent protein kinase and/or calmodulin causes the inhibition of embryogenesis. The observations presented are evidence to suggest a second messenger role for exogenous Ca(2+) during sandalwood somatic embryogenesis.

Calcimycin↗