Calcium-containing Solution Research Articles

Alteration of perlite to calcium zeolites

Hydrothermal synthesis of calcium zeolites by alteration of perlite (a rhyolitic glass) is presented. Synthetic versions of the zeolites gismondine, epistilbite and heulandite are synthesized from perlite using calcium-containing solutions, and the effects of the solution phase, pH and temperature on the distribution of the zeolitic products obtained are discussed. Transient formation of a gismondine-type zeolite during transformation of perlite to heulandite suggests a novel synthesis route for the crystallization of heulandite-type zeolites from synthetic zeolite P1.

Synthesis of CIT-3: a calcium aluminosilicate with the heulandite topology

The synthesis of CIT-3, a calcium aluminosilicate zeolite of composition CaO:Al2O3:7 7.2SiO2:6H2O possessing the HEU topology is accomplished by hydrothermal transformation of a specifically prepared zeolite P1 using calcium-containing solutions and HEU seeds. In the absence of seeds, a synthetic epistilbite phase is obtained. Details of the synthetic methodology necessary for the preparation of CIT-3 are enumerated.

Correction of hypercalcemia and hypophosphatemia by hemodialysis using a conventional, calcium-containing dialysis solution enriched with phosphorus

We report a woman with hypercalcemia and hypophosphatemia due to primary hyperparathyroidism. Hemodialysis using a phosphorus-enriched, conventional, calcium-containing dialysis solution resulted in the simultaneous correction of hypercalcemia and hypophosphatemia, resulting in a marked improvement of the patient's impaired mental status.

Haemodynamic and Metabolic Effects of Gallopamil as Additive to Calcium-containing and Calcium-free Cardioplegic Solutions in Mature Pig Hearts

Myocardial haemodynamic and metabolic effects of the calcium-channel blocker gallopamil as additive to calcium-containing (St Thomas Hospital, STH) and calcium-free (Bretschneider procaine-containing, BRT) crystalloid cardioplegic solutions were evaluated. Adult pig hearts (weight 0.330 ± 0.033 kg) were randomized to four groups and perfused with 1 litre of cold (4°C) cardioplegic solution; group A: BRT without gallopamil, n = 9, group B: BRT with gallopamil (0.4 μM), n = 8, group C: gallopamil-free STH, n = 8, and group D: STH with gallopamil (0.4 μM), n = 8. After storage at 4°C for 6 hours the hearts were reperfused with blood/Ringer solution in a modified Langendorff model for 60 min. Developed left ventricular pressure, rate-pressure product and +dP/dt were lower in gallopamil-treated hearts during reperfusion (p < 0.05), as were oxygen extraction and oxygen uptake (p < 0.05) and lactate release (p < 0.05). Myocardial blood flow was greater in gallopamil-treated hearts (p < 0.05). In hearts comparable in size and anatomy to the human heart, gallopamil added to both cardioplegic solutions reduced cardiac function and oxygen uptake despite increased myocardial blood flow. The findings suggest reduced myocardial protection after addition of gallopamil to cardioplegic solutions.

Human recombinant TNF alpha affects rat diaphragm muscle in vitro.

To study the effect of human recombinant tumour necrosis factor alpha (TNF alpha) on contracture development and changes in the ionic composition of the external bathing solution of electrically stimulated rat hemidiaphragm preparations in vitro. A triphasic controlled in vitro study using isolated tissue preparations treated in one of four ways. Phase 1 was a control period for all groups; in phase 2 preparations were exposed to TNF, TNF in calcium-free solution, TNF in magnesium-substituted calcium-free solution or no treatment (control); in phase 3 halothane was added to all preparations. The effect of anti-TNF antibody on contracture responses to TNF was studied in separate experiments. Laboratories of the Academic Unit of Anaesthesia, University of Leeds, UK. Changes in baseline tension and concentrations of potassium and sodium ions in the external bathing medium were measured for each group in each phase. In addition, changes in calcium ion concentration in the external bathing medium were measured for the control and TNF (in calcium-containing solution) groups in each phase. TNF, either in standard Krebs' solutions (p = 0.039) or calcium-free Krebs' solution (p = 0.014), produced an increased incidence of contracture development compared to control, whereas TNF in magnesium-substituted calcium-free Krebs' solution did not. In all three TNF groups there were significant increases in sodium and potassium ion concentrations compared to control, but the changes were significantly fewer in the magnesium-substituted calcium-free group than the two other TNF groups. There was a significant fall in calcium ion concentration in the TNF group compared to control. Anti-TNF antibody reduced the contracture response to halothane in the presence of TNF (p < 0.05). The results support the hypothesis that TNF acts to increase release of calcium from intracellular stores that are subject to modulation by influx of extracellular calcium or membrane depolarisation.

Spontaneous transients of [Ca 2+] i depend on external calcium and the activation of L-type voltage-gated calcium channels in a clonal pituitary cell line (AtT-20) of cultured mouse corticotropes

Spontaneous transients of [Ca 2+] i were recorded from single nonstimulated cells of a clonal pituitary cell line of corticotropes, AtT-20/D16v. The spontaneous [Ca 2+] i transients were dependent on calcium entry from the extracellular solution because they were abolished both in the absence of extracellular calcium and with the addition of cobalt to the calcium-containing extracellular solution. Calcium entry occurred through voltage-gated (VGCC) L-type calcium channels because the [Ca 2+] i transients were blocked by L-type calcium channel antagonists, e.g. nifedipine, and were unaffected by the addition of tetrodotoxin. Bay K 8644 (1 μM) induced transient increases in [Ca 2+] i, which were also blocked reversibly by either the absence of extracellular calcium or the addition of an L-type calcium channel antagonist (e.g. nifedipine). The resting levels of [Ca 2+] i and the frequency, but not the amplitude or duration, of the spontaneous [Ca 2+] i transients increased as the concentration of extracellular calcium was elevated in concentrations ranging from 1.8–7.2 mM. Potassium depolarization reversibly elevated resting levels of [Ca 2+] i and initiated the spontaneous calcium transients. These results indicate that extracellular calcium modulates the frequency of spontaneous [Ca 2+] i transients in AtT-20 cells which are caused by the activation of L-type calcium channels by a spontaneous increase in the permeability of the cell membrane to calcium.

Cutaneous Necrosis After Contact With Calcium Chloride: A Mistaken Diagnosis of Child Abuse

Necrosis of the skin after contact with calcium chloride has been described in a variety of situations, including that of oil field workers and prolonged electroencephalographic testing (contact paste). Circumscribed dystrophic dermal calcification was reported for the first time in 1935 and may follow the application of dry calcium or calcium-containing solutions. The authors report a case of percutaneous penetration of a defrosting, industrial calcium salt, which was followed by deep-dermal thigh necrosis in a child. This uncommon injury raised concern about child abuse.

Cobalt Contraction of Vascular Smooth Muscle is Calcium Dependent

Summary: We examined the mechanism by which cobalt causes contraction of vascular smooth muscle (VSM), determining whether contractile response of VSM from normotensive and hypertensive rats differed. Contraction of rings of rat thoracic aorta from normotensive Wistar-Kyoto rats (WKY) and hypertensive spontaneously hypertensive stroke-prone rats (SHRSP) in response to addition of cobalt chloride to the muscle bath was recorded. Threshold contraction occurred at 3 μM; maximum contraction occurred at 100 μM. There was no difference between rings from WKY and SHRSP in sensitivity or maximum response to cobalt. No contractile response occurred when cobalt was added to a calcium-free physiologic salt solution (PSS) to which 1.0 mM EGTA had been added. When no EGTA was added to the PSS, cobalt caused a contraction 20% as great as that observed in calcium-containing physiologic salt solution, but this small contraction was eliminated after intracellular sequestration of calcium had been prevented by treatment of the rings with cyclopiazonic acid (3 × 10−4M). A concentration-dependent contraction occurred when calcium was added back to the bath in the presence of cobalt. The contraction in response to this addition of calcium did not differ between rings from WKY and SHRSP. Threshold concentrations of cobalt produced marked potentiations of contractile responses to either norepinephrine (NE) or KCl. We conclude that cobalt causes contraction by activating both voltage-sensitive and receptor-operated calcium channels in the plasma membrane. Cobalt also caused release of intracellularly sequestered calcium. There was no difference between the responses to cobalt of VSM from WKY and SHRSP.

Cobalt Contraction of Vascular Smooth Muscle is Calcium Dependent

We examined the mechanism by which cobalt causes contraction of vascular smooth muscle (VSM), determining whether contractile response of VSM from normotensive and hypertensive rats differed. Contraction of rings of rat thoracic aorta from normotensive Wistar-Kyoto rats (WKY) and hypertensive spontaneously hypertensive stroke-prone rats (SHRSP) in response to addition of cobalt chloride to the muscle bath was recorded. Threshold contraction occurred at 3 microM; maximum contraction occurred at 100 microM. There was no difference between rings from WKY and SHRSP in sensitivity or maximum response to cobalt. No contractile response occurred when cobalt was added to a calcium-free physiologic salt solution (PSS) to which 1.0 mM EGTA had been added. When no EGTA was added to the PSS, cobalt caused a contraction 20% as great as that observed in calcium-containing physiologic salt solution, but this small contraction was eliminated after intracellular sequestration of calcium had been prevented by treatment of the rings with cyclopiazonic acid (3 x 10(-4) M). A concentration-dependent contraction occurred when calcium was added back to the bath in the presence of cobalt. The contraction in response to this addition of calcium did not differ between rings from WKY and SHRSP. Threshold concentrations of cobalt produced marked potentiations of contractile responses to either norepinephrine (NE) or KCl. We conclude that cobalt causes contraction by activating both voltage-sensitive and receptor-operated calcium channels in the plasma membrane. Cobalt also caused release of intracellularly sequestered calcium. There was no difference between the responses to cobalt of VSM from WKY and SHRSP.

The effect of EDTA on contractile responses of guinea-pig trachea in calcium-free medium and on the recovery of the contractile responses in calcium-containing solution

1. 1. Acetylcholine (0.1 mmol/l) and KCl (80 mmol/l) induce contractile responses in guinea-pig trachea. 2. 2. In the absence of extracellular Ca, contractile responses to ACh or KCl decrease as the preincubation time or the EDTA concentration increases. 3. 3. Exposure of the tissue to Ca-free medium decreases the basal tone. 4. 4. Prolonged incubation in the presence of EDTA (1 mmol/l) promotes a delay in the recovery of the tonic component of the contraction elicited subsequently by acetylcholine and KCl in physiological salt solution, and abolishes the phasic one.

Calcium released by photolysis of DM-nitrophen triggers transmitter release at the crayfish neuromuscular junction.

1. Spontaneous and evoked transmitter release at the crayfish neuromuscular junction were potentiated in response to photolytic release of calcium from the 'caged' calcium compound DM-nitrophen, which had previously been injected into presynaptic terminals. 2. The amount of calcium released from DM-nitrophen photolysis depends on the concentration of DM-nitrophen, its photoproducts, Ca2+, Mg2+, H+, ATP and the cell's native buffer. Since none of these are known in the crayfish terminal, the study was conducted in a qualitative fashion. 3. Photolytic release of calcium from DM-nitrophen increased excitatory junctional potentials (EJPs) by a range of 2-31 times over control values and the miniature excitatory junctional potential (MEJP) frequency increased from resting values of 1-10 quanta/s to 3000-11,000 quanta/s. 4. Extracellular calcium was not required for the light-evoked asynchronous release of transmitter. Calcium-bound DM-nitrophen previously pressure injected into crayfish presynaptic terminals increased the MEJP frequency from resting values of 1-8 quanta/s to 800-10,000 quanta/s during photolysis in a calcium-free cobalt Ringer solution. 5. Iontophoresis of calcium-free DM-nitrophen into presynaptic terminals released transmitter upon photolysis, but only in a calcium-containing Ringer solution. This suggests that DM-nitrophen is capable of binding calcium once injected into terminals, but this is dependent on the presence of external calcium. 6. Photolysis of DM-nitrophen at lower light intensities produced a slower rate of transmitter release. 7. Brief light exposures, i.e. those which photolysed 5-20% of the DM-nitrophen, resulted in a rapid decay of postsynaptic responses on extinguishing the light, due to rebinding of photolytically released calcium to unphotolysed DM-nitrophen. Longer light exposures which completely photolysed DM-nitrophen, leaving only the low affinity photoproducts, produced a slow decay of transmitter release after the light pulse, presumably due to the active extrusion of calcium from the presynaptic terminals. 8. During photolysis of DM-nitrophen, the time courses of changes in EJP amplitude and MEJP frequency were different, indicating that the two measures of transmitter release were not linearly related. 9. MEJP frequency and EJP amplitudes during DM-nitrophen photolysis were fitted to a 'non-linear summation model' in which photolytically released calcium sums with calcium entering during an action potential to evoke transmitter release with a calcium co-operativity of five.

Effect of chronic intravenous calcitriol on parathyroid function and set point of calcium in dialysis patients with refractory secondary hyperparathyroidism

This study evaluates the effect of intravenous calcitriol on parathyroid function and ionized calcium-PTH sigmoidal curve obtained during low- and high-calcium haemodialysis in 10 patients with osteitis fibrosa whose secondary hyperparathyroidism was refractory to conventional therapy. After 4 months of intravenous calcitriol, serum ionized calcium increased from 1.28 +/- 0.08 to 1.37 +/- 0.11 mmol/l (P less than 0.001), serum phosphate from 1.54 +/- 0.18 to 1.79 +/- 0.4 mmol/l (P NS), serum calcitriol from 16.7 +/- 9.9 to 34.3 +/- 6.4 pg/ml (P less than 0.001), while alkaline phosphatase decreased from 366 +/- 340 to 226 +/- 180 IU/l (P less than 0.05), osteocalcin from 46.4 +/- 20 to 34.5 +/- 15.3 ng/ml (P less than 0.05), and basal intact PTH from 1069 +/- 700 to 305 +/- 270 (P less than 0.01). Basal PTH started to decrease after 1 month of treatment prior to the increase in the ionized calcium. Because of hypercalcaemia the dialysate calcium was decreased from 1.75 to 1.5 mmol/l in three of five patients on haemodialysis, and calcium-containing solutions were replaced by calcium-free fluids in four of five patients on haemodiafiltration. Calcitriol dose, at the first month of therapy was 5.6 +/- 0.8 micrograms/week, but it was successively decreased because of hypercalcaemia to a final dose of 3.6 +/- 1.3 micrograms/week. After intravenous calcitriol the ionized calcium-PTH sigmoidal curve shifted to the left and downward. Maximally stimulated PTH and maximally inhibited PTH obtained during low- and high-calcium dialysis significantly decreased, as well as the ratio of basal PTH/PTHmax and the set point of calcium.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium dependence of serotonin-evoked conductance in C6 glioma cells.

Whole-cell membrane currents and imaging of intracellular calcium concentrations ([Ca2+]i) were used to investigate the role of calcium in a response to serotonin of C6 glioma cells. Activation of a high-affinity serotonin receptor induced a transient rise in calcium concentration in these cells and activated a predominantly potassium conductance, with a small chloride component. Perfusion of the cytoplasm with an internal solution containing high calcium concentration induced similar but prolonged increase of membrane conductance. The responsiveness of C6 cells to serotonin was negatively correlated with the concentration of the unbound calcium chelator BAPTA when BAPTA-buffered calcium-containing intracellular solutions were used. Responses to serotonin persisted in the absence of external calcium, decreased gradually, and then recovered partially after replenishment of extracellular calcium. These findings substantiate the direct role of intracellular calcium in mediating the serotonin response, and indicate that serotonin-induced release of calcium from intracellular stores is sufficient for the activation of conductance in the C6 glioma cell line.

The sensitivity of adrenergic varicosities to the 3H-noradrenaline-releasing effect of potassium

After the loading of incubated, homogeneously innervated tissues with 3H-noradrenaline (monoamine oxidase and catechol-O-methyl transferase inhibited, calcium-containing solution) high K+ released the 3H-amine from adrenergic varicosities. In paired experiments the sensitivity of rat atria to high K+ exceeded that of vasa deferentia. In the rat vas deferens the releasing effect of high K+ was enhanced by drugs or procedures which induce a carrier-mediated outward transport of 3H-noradrenaline, i.e., by ouabain, by glucose deprivation and by hypoxia. In the presence of extracellular calcium desipramine failed to affect the releasing effect of high K+ (except in the absence of glucose or during hypoxia), but in the absence of calcium desipramine reduced it. Apparently, whenever the axoplasmic levels of 3H-noradrenaline are increased, high K+ is able to induce some carrier-mediated outward transport of the 3H-amine. It is suggested that "organ differences" with respect to the sensitivity to high K+ may well be due to hypoxia (plus some lack of glucose) of those varicosities that had been loaded with 3H-noradrenaline. The risk of storage of 3H-noradrenaline in hypoxic varicosities appears to be greater in incubated than in perfused organs, and in the former it is greater in sparsely than in densely innervated tissues.

Calcium Dependence of Contractile Activation of Isolated Sheep Urethra II: Responses to Exogenous Noradrenaline

Isolated smooth muscle of sheep urethra responded to exogenous noradrenaline (NA) with a concentration-dependent contraction. After exposing the preparations for 30 min. to calcium-free medium, NA in a submaximal concentration was still able to produce a contractile response amounting to 36% of control value in calcium-containing solution. Readmission of calcium (administered cumulatively) restored the response in a concentration-related fashion to 85% (at 5 mM calcium) of control level. Nifedipine and verapamil failed to inhibit these graded calcium contractions in the presence of NA. Verapamil and diltiazem also failed to significantly prevent contraction induced by NA in a submaximum concentration, but nifedipine showed a concentration-dependent inhibitory effect, with a potency 1000 times lower than that observed on K+ (124 mM) induced contractions. In calcium-free medium, repeated applications of NA at 30 min. intervals, induced a progressive reduction in contractile amplitude. Nifedipine or verapamil did not affect the time course for recovery of NA-induced contraction when the preparations were returned to calcium containing medium, but the recovery was blocked almost completely by lanthanum. Furthermore, lanthanum abolished the remaining NA contraction in calcium-free medium. The results suggest that NA-induced contraction in isolated sheep urethra is dependent on both influx of extracellular calcium and on release of intracellular calcium. Calcium influx for contractile activation and refilling of intracellular stores seem to occur through membrane channels that can only partly be blocked with calcium antagonists.

Role of the sarcolemma in triggered propagated contractions in rat cardiac trabeculae.

We have recently described that after contractions propagate through multicellular cardiac muscle preparations. These propagating contractions are triggered in damaged regions of rat right ventricular trabeculae during relaxation of electrically stimulated twitches. Propagation of triggered contractions has been attributed to calcium ions that diffuse along the preparation, causing calcium-induced calcium release from the sarcoplasmic reticulum in adjacent cells. In the present study we have investigated a possible role of the sarcolemma and delayed afterdepolarizations (DADs) in the initiation and propagation of triggered propagated contractions (TPCs) in multicellular preparations. We studied whether 1) TPCs are accompanied by delayed sarcolemmal depolarizations, 2) such depolarizations mediate local contraction, and 3) an intact sarcolemma is required for propagation of contractions. TPCs that remained stable for prolonged periods of time could be induced by trains of 15 stimuli (2 Hz, 15-second intervals) at lowered temperature (19-21 degrees C) of the superfusing Krebs-Henseleit medium and a [Ca(2+)]o of 1.0-1.5 mM. Although TPCs could be induced at 38 degrees C and a [Ca2+]o of 3.0-4.0 mM, they disappeared within 10 minutes. Force was measured with a silicon strain gauge; length and shortening of sarcomeres were measured at two sites of the muscle using laser diffraction techniques. Membrane potential was measured with flexible microelectrodes. Saponin was used to selectively render the sarcolemma permeable to small ions and molecules. Propagation velocity of TPCs in intact trabeculae varied from 1.7 to 13.4 mm/sec at 19-21 degrees C. TPCs were accompanied by DADs that could reach threshold and induce triggered arrhythmias. Changes in latency, duration, and force of TPCs, induced by changing [Ca(2+)]o or the number of conditioning stimuli, were closely matched by changes in latency, duration, and amplitude of DADs; DADs consistently preceded TPCs, on average by 60 msec. Local heating of the muscle, by applying a current through an insulated platinum wire (diameter 100 microns) that touched the muscle, interrupted propagation of TPCs reversibly. DADs were, in the absence of a local contraction, still recorded distal to the heated site. In muscles that were treated with saponin and exposed to solutions approximating the intracellular milieu, spontaneously occurring local contractions that propagated in both directions (at velocities of 70-200 microns/sec) were elicited at a bathing calcium concentration of approximately 0.6 microM. Below this threshold, propagated contractions could be triggered by pressure ejection of a calcium-containing solution from a microelectrode positioned close to the trabecula.(ABSTRACT TRUNCATED AT 400 WORDS)

Inositol phosphates formed in rat aorta after α1-adrenoceptor stimulation are inhibited by forskolin

Rat aortic smooth muscle rings without endothelial cells were subjected to alpha 1-adrenoceptor stimulation. We measured the contractile state of the smooth muscle cells and the formation of inositol phosphates (InsPs) on receptor stimulation. Using different extracellular calcium-containing solutions (2.5 mM, 0.1 mM and Ca(2+)-free) enabled us to discriminate three contractile phases after noradrenaline (10(-5) M) stimulation: an initial fast contraction (15 s) and a fast and slow component of the sustained contraction, which was established 10 min after stimulation. Under normal calcium conditions in the presence of 10 mM LiCl the formation of Ins(1,4,5)P3 was increased predominantly after stimulation, while the formation of Ins(1,3,4)P3, Ins(1,3,4,6)P4, Ins(1,3,4,5)P4, Ins(3,4,5,6)P4 and InsP5/InsP6 was also stimulated. The cAMP-inducing agent forskolin (0.5 microM) induced a relaxation of the basal tone and increased the level of the InsP4 isomers. The noradrenaline-induced contractile responses as well as the formation of InsP fractions mentioned were inhibited by forskolin. Further an increase in the formation of phosphatidylinositol bisphosphate was observed. It is concluded that in rat aorta InsPs and in particular Ins(1,4,5)P3 is involved in the different contractile phases caused by alpha 1-adrenoceptor stimulation. The relaxation induced by forskolin under these circumstances could be explained by an interaction of forskolin, most likely via the formation of cAMP, with InsPs formation at the level of phospholipase C activation.

Evaluation of a new calcium containing cardioplegic solution in the isolated rabbit heart in comparison to a calcium-free, low sodium solution

Isolated perfused rabbit hearts were studied to compare the effects of 3 hour ischemic arrest following either calcium-free or calcium-containing cardioplegia, on the recovery of isovolumic function of the left ventricle, coronary flow, release of creatine phosphokinase and myocardial water content. The hearts perfused with the calcium-containing solution (Ca 0.5 mmol/L) showed better recovery of the developed pressure in the left ventricle, and its first derivative and compliance. Coronary flow at a constant perfusion pressure was better restored during reperfusion in the hearts with calcium-containing solution. The release of less CPK and a lower water content were also observed in the hearts reperfused with calcium-containing solution. We concluded that calcium-containing cardioplegic solution with a high concentration of magnesium (10 mmol/L) was superior to calcium-free solution for myocardial protection.

Effects of Constituents of Beli (Aegle marmelos) on Spontaneous Beating and Calcium-Paradox of Myocardial Cells1

Effects of methanolic extract of root bark of Beli (Aegle marmelos Corr.), an Ayurvedic crude drug used for heart diseases, and constituents isolated from the extract on spontaneous beating of cultured mouse myocardial cells were examined. The extract at a concentration of 100 micrograms/ml inhibited the beating rate by approximately 50%. Among the isolated constituents, aurapten was the most potent inhibitor; the IC50 of aurapten is 0.6 microgram/ml, which is comparable with that of verapamil, a calcium antagonist. Addition of aurapten at concentrations higher than 1 microgram/ml significantly reduced the ratio of morphologically changed myocardial cells which originated from calcium overload caused by successive treatment with calcium-free and calcium-containing solutions.

A cytosolic sperm factor stimulates repetitive calcium increases and mimics fertilization in hamster eggs

Microinjection of cytosolic sperm extracts into unfertilized golden hamster eggs caused a series of increases in cytoplasmic free calcium, Ca2+i, and membrane hyperpolarizing responses, HRs. These HRs and Ca2+i transients are similar to those seen during in vitro fertilization of hamster eggs. The sperm factor that is responsible for causing these effects appears to be of high molecular weight and protein based. Injection of sperm factor activated eggs and mimicked fertilization in causing repetitive HRs in the presence of phorbol esters and in sensitizing the egg to calcium-induced calcium release. Since these effects cannot be mimicked by injecting G-protein agonists or calcium-containing solutions, it seems unlikely that a receptor-G-protein signalling system is involved at fertilization. These data instead suggest a novel signal transduction system operates during mammalian fertilization in which a protein factor is transferred from the sperm into the egg cytoplasm after gamete membrane fusion.