Nina Grosman

Plasma morphine concentrations during chronic oral administration in patients with cancer pain

Abstract Plasma concentrations of morphine were studied in 16 patients with chronic pain due to advanced cancer, treated with regular doses of morphine chloride by the oral route. Doses ranged from 20 to 125 mg every 4 h and a significant, positive, linear correlation was found between dose (range 0.22–3.01 mg/kg) and mean plasma concentration (range 22–364 ng/ml). The profile of the 4 h concentration curve is described and found to be subject to considerable, individual variation. The present investigation supports the experience that good pain relief can be obtained, if individual requirements as to dose and dose interval are taken into consideration.

Effect of Divalent Cations and Metabolic Energy on the Anaphylactic Histamine Release from Rat Peritoneal Mast Cells

Histamine release induced by the antigen from mast cells obtained from actively sensitized rats was enhanced by the same concentration of calcium in the medium, irrespective of whether the mast cells

Histamine release from isolated rat mast cells: effect of morphine and related drugs and their interaction with compound 48/80

Morphine, codeine, and pethidine induced histamine release from isolated rat mast cells in the same concentration range. The histamine release induced by morphine and by codeine occurred rapidly, in contrast to the release induced by pethidine. The effect of morphine was reduced by the presence of calcium, enhanced by magnesium, and unaffected by phosphatidyl serine. Pretreatment of the cells with the ionophore A23187 inhibited the response to morphine, indicating a requirement for intracellular calcium.The release induced by morphine and by codeine was inhibited by antimycin A, but the release induced by pethidine was unaffected. The effect of morphine was inhibited by both naloxone and codeine, and naloxone also reduced the release induced by codeine. The effect of pethidine was inhibited by codeine, whereas the influence of naloxone was less pronounced.Preincubation of cells with lower concentrations of morphine reduced the response to a subsequent exposure to morphine. The release induced by compound 48/80 was similarly inhibited after preincubation with morphine as well as after preincubation with codeine and with pethidine. In contrast, preincubation with pethidine enhanced the effect of subsequent incubation with pethidine. Preincubation with low concentrations of compound 48/80 reduced the response to compound 48/80 in the absence of calcium, but was without effect in the presence of calcium.It is suggested that morphine, codeine, pethidine, and naloxone act on common or closely related sites on the mast cell and that these sites may account for the action of compound 48/80 as well. The results indicate similar mechanisms for the histamine release induced by morphine and by codeine, whereas pethidine clearly has a different mode of action.

The influence of tetradecanoyl-phorbol-acetate (TPA) on histamine release from isolated rat mast cells

A detailed investigation of the influence of tetradecanoyl-phorbol-acetate (TPA) on isolated rat mast cells was undertaken in order to explore the possible involvement of protein kinase C in histamine release. TPA alone could induce histamine release in a medium without calcium, whereas 1 mM CaCl2 suppressed the release. TPA in combination with a low concentration of the ionophore A23187 induced a considerable histamine release. Preincubation with TPA followed by incubation with the ionophore induced a similar release at low concentrations of TPA (≦2.5 nM) whereas the response was reduced at higher concentrations of TPA. The inhibition after preincubation with TPA was almost at a maximum within 2 min and was due to a decreased rate of release. TPA could also increase antigen-induced histamine release. After preincubation the potency of low concentrations of TPA increased, whereas higher concentrations (50 nM) became inhibitory. The effects of preincubation were almost fully expressed after 2 min and were not due to altered kinetics of the release. The interaction of oleoylacetylglycerol (OAG) with the ionophore A23187 and with antigen resembled that of TPA, but OAG was considerably less potent. Preincubation with TPA was inhibitory to the histamine release induced by compound 48/80, particularly in the absence of calcium. The release induced by TPA and the ionophore or antigen was calcium-dependent and energy-requiring, and the effects of TPA persisted after washing the cells before exposure to antigen or the ionophore. Preincubation with the protein kinase C inhibitor isoquinolinesulfonyl-methylpiperazine (H-7) slightly enhanced the histamine release induced by the combination of TPA and the ionophore. The suppression exerted by preincubation with TPA on ionophore- and antigen-induced release was counteracted by H-7. The results indicate that only the inhibitory effects of protein kinase C are affected by H-7. Although not conclusive, the results are compatible with an involvement of protein kinase C in both the enhancing and the inhibitory effects of TPA on mast cell histamine release.

Inhibitory effect of phloretin on histamine release from isolated rat mast cells

The ability of the flavonoid phloretin to inhibit histamine release from rat mast cells varied considerably with the releasing agent investigated. The response to the combination of the ionophore A23187 and the phorbol ester TPA and to suboptimal concentrations of the ionophore (0.5 μ M) was potently inhibited (IC50 about 5 μM), whereas phloretin was less potent against responses to the ionophore (1 μM) IC50 of 17 μM), to antigen alone and in combination with TPA (IC50 of 30–50 μM), to TPA in the absence of calcium (IC50 of 50 μM) and to compound 48/80 in the absence and presence of calcium (IC50 of 60–90 μM). The inhibition by phloretin at concentrations above 10μM was partly counteracted by glucose (5 mM) indicating effects on oxidative metabolism. The flavonoid quercetin was equally potent in inhibiting histamine release induced by antigen, the ionophore at different concentrations and in combination with TPA (IC50 of 20μM). Although not conclusive, the results are consistent with an inhibition of protein kinase C by phloretin at concentrations below 10 μM. At higher concentrations unspecific actions become apparent and phloretin therefore seems to be of limited utility as a probe for signal-pathways in cell responses.

Binding of45Calcium to isolated rat mast cells in connection with histamine release

The time courses for histamine release and uptake of45Ca were compared on isolated rat mast cells after stimulation under different experimental conditions with antigen, compound 48/80, ATP, or the ionophore A23187. Except for ATP the results did not show a time-dependent correlation between histamine release and45Ca uptake.The uptake of45Ca under conditions where membrane-bound calcium is utilized for optimal anaphylactic histamine release did not differ from that of controls, whereas the presence of45Ca in the incubation medium led to a substantial uptake without influence on the histamine release.The uptake of45Ca induced by antigen or compound 48/80 was completely inhibited by antimycin A as confirmed by the use of two different methods. In addition, an energy-dependent restitution of the permeability properties of the plasma membrane seemed to follow histamine release. Antimycin A partly reduced the uptake of45Ca after stimulation with ATP, and did not affect binding following exposure of the cells to the ionophores A23187 or X537A.The ionophore A23187 was able to reduce the45Ca content of mast cells previously loaded with the isotope. Mast cells pretreated with A23187 in the absence of extracellular calcium did, after washing, accumulate substantial amounts of45Ca without release of histamine.The results suggest that only small amounts of calcium are required to trigger histamine release and that studies with45Ca do not distinguish between specific uptake of calcium and nonspecific equilibration secondary to morphological secretory changes.

Histamine release from isolated rat mast cells induced by opiates: effect of sterical configuration and calcium

The stereospecificity of the action of opiates on rat mast cells was investigated by means of thel-andd-isomers levorphanol and dextrorphan. The dose-response curves for histamine release induced by the 2 drugs were of a similar shape with a maximum at 2×10−3M and a pronounced minimum at 5×10−3M. At concentrations below 5×10−3M the effect of both drugs resembled that of morphine, i.e. the release occurred rapidly and inhibition was observed with naloxone, codeine, and antimycin A. Levorphanol, dextrorphan, and the antagonist levallorphan at concentrations above 5×10−3M seemed to be toxic to mast cells.The uptake of45Ca in connection with histamine release induced by pethidine, levorphanol, and dextrorphan was lower than that of control cells, whereas the uptake induced by morphine did not differ from that of controls. The inhibition of compound 48/80-induced histamine release by morphine was paralleled by a reduced45Ca uptake.The time course for the inhibitory effect of preincubation with morphine was similar for the histamine release induced by morphine and by compound 48/80. Washing of the cells after preincubation with morphine was without effect on the inhibition of morphine-induced histamine release, whereas the inhibition of compound 48/80. was reduced.The present observations with morphine and compound 48/80 support our previous impression of similarities in their mode of action, but a mechanism implying an interference by morphine with the disposition of calcium could also account for the findings. The observed antagonism between morphine and calcium resembles that of opiate receptors, but histamine release induced by opiates does not involve sterospecific opiate receptors.

The influence of phosphatidyl serine on the release of histamine from isolated rat mast cells induced by different agents

The influence of phosphatidyl serine (PS) on histamine release from isolated rat mast cells induced by antigen, compound 48/80, adenosine-5′-triphosphate (ATP), the ionophore A23187, and decylamine was studied. PS enhanced antigen-induced release but inhibited the release caused by compound 48/80, A23187, and decylamine. PS did not influence the release induced by ATP. The different effects of PS on the action of the various histamine releasing agents do not conform to a unifying model for the action of PS on the release process. Possible interactions between PS and the agents in the incubation medium as well as at specific reactive sites on the plasma membrane might explain some of the effects of PS. Consequently, the results cannot be used as evidence for the existence of basic differences in the release process induced by various calcium-and energy-dependent releasing agents.

Similar effects of ether phospholipids, PAF and lyso-PAF on the Ca2+-ATPase activity of rat brain synaptosomes and leukocyte membranes

The present study is an extension of our previous work with the antineoplastic ether phospholipid ET-18-OCH3 (edelfosine), which was shown to affect the activity of the Ca(2+)-ATPase of rat brain synaptosomes and peritoneal leukocyte membranes. The effect of ET-18-OCH3 was compared with that of the 16-carbon chain analogue ET-16-OCH3 as well as with the structurally related 16- and 18-carbon PAFs (platelet-activating factors) and lyso-PAFs. In addition, the two alkylphosphocholines D-20166 and D-21266 (perifosine) were included in the investigation. The influence of all of the compounds followed the same pattern, i.e., the Ca(2+)-ATPase activity of the synaptosomes was increased over a relatively narrow concentration range (peak at 20-30 microM) and that of the leukocyte membranes was inhibited in a concentration-dependent manner by 10-50 microM concentrations of the drugs. Ether phospholipids with an 18-carbon chain at C-1 were more potent than those with a 16-carbon chain. All of the compounds increased the activity of the synaptosomal ATPase to the same extend (ca. 50%). With the exception of lyso-PAF, all inhibited the enzyme activity of leukocyte membranes by 60-70%, whereas lyso-PAF was less effective (ca. 50% inhibition). The concentration range of activity for PAF and lyso-PAF indicates that their effect on the enzyme activity was caused by receptor-independent mechanisms. The ether phospholipids and alkylphosphocholines are suggested to act by accumulating in the membranes and thereby altering the character of the lipid environment of the enzyme rather than by a direct interaction with the Ca(2+)-ATPase.

Effects of the ether phospholipid AMG-PC on mast cells are similar to that of the ether lipid AMG but different from that of the analogue hexadecylphosphocholine.

The ether lipid AMG (1-O-hexadecyl-2-O-methylglycerol) has previously been shown to have both enhancing and inhibitory effects on histamine release from isolated rat mast cells. In addition, a synergistic interaction with the phorbol ester TPA indicated protein kinase C activation. In the present investigation the effects of the related ether phospholipid AMG-PC (1-O-hexadecyl-2-O-methylglycero-3-phosphocholine) and the analogue hexadecylphosphocholine (miltefosine (HPC) are compared with those of AMG. HPC had only inhibitory effects, in contrast to AMG-PC which acted similarly on histamine release induced by compound 48/80, but had dual influence on responses to antigen and the ionophore A23187 and mainly exhibited a synergistic interaction with combinations of the ionophore and TPA. The influence of AMG-PC differed from that of AMG in some aspects whereas the character of its synergistic interaction with A23187 resembled that of AMG, in particular after pre-incubation with TPA. The results show that HPC does not share all biological activities of the antineoplastic ether lipids. They indicate that the effects of AMG-PC under appropriate conditions may be due to activation of protein kinase C but do not permit a distinction between direct effects and indirect through metabolic conversion to AMG.