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PubMedDate not supplied

Effects of PGE2 and colchicine on the intestinal fluid volume.

a) Colchicine, prostaglandin E2 (PGE2) and carbachol increase the intestinal fluid volume in the rat. b) The effect of carbachol and prostaglandin E2 is augmented whereas that of colchicine is diminished in the pithed rat. c) The effect of colchicine is diminished in anaesthesia whereas that of PGE2 remains unchanged. d) The effect of PGE2 and of colchicine are both inhibited by atropine. e) The effects of PGE2 and of colchicine are both enhanced by phentolamine. f) Pretreatment with indomethacin decreased the effect of colchicine whereas that of PGE2 remained unchanged. g) The PGE2-induced increase in intestinal fluid volume may partly be mediated by a peripheral mechanism involving acetylcholine receptors. h) The increase in intestinal fluid volume by colchicine can mainly be explained by a central action of the drug which is mediated by cholinergic neurones.

Animals↗

PubMed1995

Redistribution and fate of colchicine-induced alkaline phosphatase in rat hepatocytes: possible formation of autophagosomes whose membrane is derived from excess plasma membrane.

The redistribution and fate of colchicine-induced alkaline phosphatase (ALPase) in rat hepatocytes were investigated by electron microscopic enzyme cytochemistry and biochemistry. ALPase activity markedly increased in rat hepatocytes after colchicine treatment (2.0 mg/kg body weight, intraperitoneal injection). At 20-24 h after colchicine treatment, the liver showed the highest activity of ALPase. Thereafter, ALPase activity decreased and returned to normal levels at 48 h. In normal hepatocytes from control rats, ALPase activity was seen only on the bile canalicular membrane. However, at 20-24 h after colchicine treatment, colchicine-induced ALPase was redistributed in the sinusoidal and lateral (basolateral) membranes as well as in the bile canalicular membrane. At 30-36 h after colchicine treatment, ALPase activity on the basolateral membrane gradually decreased. In contrast, ALPase in the bile canalicular membrane increased along with the enlargement of bile canaliculi, suggesting that ALPase in the basolateral membrane had been transported to the bile canalicular membrane. Furthermore, ALPase-positive vesicles, cisternae and autophagosome-like structures were frequently seen in the cytoplasm. ALPase was also positive in some lysosomal membranes. ALPase in hepatocytes at 48 h after colchicine treatment returned to almost the same location as in control hepatocytes. Altogether, it is suggested that excessively induced ALPase is at least partially retrieved by invagination of the bile canalicular membrane and then transported to lysosomes for degradation. In addition, this study indicates that excess plasma membrane might be a possible origin of autophagosomal membrane.

Alkaline Phosphatase↗

PubMed1984

Axonal microtubules necessary for generation of sodium current in squid giant axons: II. Effect of colchicine upon asymmetrical displacement current.

Effect of internal colchicine on asymmetrical displacement currents was studied by internally perfusing squid giant axons with a solution containing colchicine. It was found that (1) asymmetrical displacement currents were composed of two parts; colchicine-sensitive and colchicine-resistant; that (2) the colchicine-sensitive part had a definite rising phase while the colchicine-resistant one showed an instantaneous jump, followed by exponential decay; and that (3) the colchicine-sensitive part related to normal Na channels.

Animals↗

PubMed1988

Stress-induced blocking of cell division in the colchicine arrest technique.

Previous studies have shown that procedures commonly used in studies of cell population kinetics in laboratory animals cause a transient block of the entrance of cells into mitosis. The purpose of the present study was, therefore, to examine whether the handling of animals in conjunction with the administration of colchicine affects the results obtained by the metaphase arrest technique. Groups of rats were injected with colchicine or saline at 1300 h and sacrificed at regular intervals during the following 140 min. Histological sections of the palatal mucosa were produced and the number of metaphases was assessed in the epithelium. In both the saline-treated and colchicine-treated groups the numbers of metaphases decreased immediately after injection and reached a minimum within 30 min. After that time a transient increase was observed in the saline group, whereas the number of metaphases in the colchicine-treated group increased continuously during the experimental period. These results indicate that colchicine takes effect after a delay period of 30 min and that the handling procedures in conjunction with the administration of colchicine provoke a transient block of the entry of cells into mitosis. The second part of the study was designed in such a way that the number of metaphases collected during a 2 h period under the influence of stress induced by injection of colchicine could be compared with the number of metaphases collected during the same time period without the influence of stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Albinism↗

PubMed1998

Effect of colchicine on nerve growth factor-induced leukocyte accumulation and thermal hyperalgesia in the rat.

In addition to its neuronal effects, nerve growth factor (NGF) is known to act on inflammatory and immune cells. The aim of the present study was to investigate the effect of colchicine on NGF-induced leukocyte accumulation and thermal hyperalgesia. Initial experiments showed that intradermal injection of recombinant human (rh) NGF (0.8 and 4 microg) caused a longlasting increase in tissue myeloperoxidase (MPO) indicating leukotactic activity of NGF. Colchicine (0.3 and 1 mg/kg) attenuated the NGF (0.8 and 4 microg)-induced increase in tissue myeloperoxidase (MPO) as determined 6 h after NGF application. Intraplantar injection of NGF into the rat hindpaw caused a decrease in thermal nociceptive threshold, which, at 4 microg NGF, was accompanied by moderate (about 35% increase in paw volume) edema. The thermal hyperalgesia was evident 20 min after injection and lasted less than 4 h. Colchicine (0.3 and 1 mg/kg) had no significant effect on NGF-induced edema, but reduced NGF-induced thermal hyperalgesia. Colchicine (1 mg/kg) did not significantly reduce thermal hyperalgesia produced by intraplantar bradykinin, prostaglandin E1, or 5-hydroxytryptamine. Treatment of rats with a dose of indometacin (2 mg/kg) that was sufficient to block cyclooxygenase had no significant effect on NGF-induced thermal hyperalgesia or edema. In vitro, colchicine (0.4-12 microg/ml) did not significantly influence NGF (10 ng/ml)-induced histamine release from rat peritoneal cells, suggesting that a mast cell stabilizing effect of colchicine did not contribute to inhibition of NGF-induced thermal hyperalgesia. The results show that NGF causes localized indometacin-resistant thermal hyperalgesia that can be blocked by the microtubule disrupting agent colchicine. These results raise the possibility that a mechanism by which NGF produces peripheral sensitization is related to its leukotactic effect.

Animals↗

PubMed2000

Dapsone and colchicine inhibit adhesion of neutrophilic granulocytes to epidermal sections.

A frozen section adhesion assay was used to study the influence of dapsone and colchicine on cell-cell adhesion between neutrophils and epidermal cells. Sections were prepared from small punch biopsies from healthy donors after preincubation with IFN-A. Freshly prepared neutrophils were activated with TNF-. or PAF after exposure to dapsone or colchicine, incubated on these sections, and the adhered cells were enumerated after washing. In the presence of dapsone (at concentrations of 0.1-80 Ig/ml) adherence of neutrophils could be blocked dose-dependently and 50% inhibition of adhesion was achieved at a concentration of 10 Ig/ml. Colchicine at concentrations of 10-200 ng/ml inhibited neutrophil binding with a clear correlation between inhibition and colchicine concentration. At a colchicine concentration of 110 ng/ml, 50% blocking was achieved. Since the function of CD11b/ paragraph signCD18 is necessary for neutrophil adhesion in this assay, we monitored CD11b expression on neutrophils after dapsone and colchicine exposure. CD11b expression on neutrophils was significantly reduced 5 h after incubation with dapsone at a concentration of 80 Ig/ paragraph signml, whereas no effects of colchicine on CD11b expression could be demonstrated. Our study showed that both drugs significantly inhibited adhesion between neutrophils and the epidermis.

Cell Adhesion↗

PubMed1998

Mechanical sensitivity of muscle afferents in a nerve treated with colchicine.

The experiments reported here demonstrate that the mechanical sensitivity of peripheral nerve fibres typically seen after injury can be induced without overtly injuring the nerve, but by simply applying colchicine topically to the nerve. In cats anaesthetised with pentobarbitone sodium, the medial gastrocnemius nerve was exposed and 10 mM colchicine applied topically for 15 min. The animals recovered from the operation normally and showed no subsequent motor deficit. Six days later animals were re-anaesthetised, a laminectomy carried out and responses recorded in single afferents at the level of the dorsal root. It was found that many afferents, particularly those with conduction velocities in the group II-III range, had become sensitive to local mechanical stimulation of the nerve in the region treated with colchicine and showed slowly adapting responses to stretch of the nerve. Many of the smaller fibres exhibited spontaneous activity. Mechanically sensitive afferents exhibited impulse conduction blocks at the colchicine-treated site. Some afferents, which appeared to conduct impulses normally through the treated region, were associated with muscle receptors having normal response properties. However, other muscle receptors were clearly abnormal and were insensitive to muscle stretch or contraction or exhibited only phasic responses. When the nerve was cut proximal to the colchicine-treated site, some, but not all, spontaneous activity was abolished. It was subsequently shown using a collision technique that the activity in some axons had its origin in the cell body in the dorsal root ganglion. In one experiment, it was shown that after nerve section proximal to the colchicine-treated region three of five axons switched their activity from a peripheral to a central origin. It is postulated that colchicine disrupts fast axonal transport of mechanically sensitive or voltage-sensitive ion channels, from the cell body to the peripheral terminals of the axons, leading to an accumulation of these channels at the treated site. This induces mechanical sensitivity and spontaneous activity. It is postulated that interruption of a retrogradely transported signal induces the spontaneous activity in the cell body. These experiments suggest that an important influence is exerted by the cell body on the peripheral terminals of mechanoreceptors to confer on them their normal response properties.

Action Potentials↗

PubMed2001

Colchicine myopathy: a vacuolar myopathy with selective type I muscle fiber involvement. An immunohistochemical and electron microscopic study of two cases.

Colchicine, a microtubule polymerization inhibitor, can very occasionally induce myopathy. We report two cases of colchicine myopathy. Both patients presented with myalgia and proximal muscle weakness. The first patient, an 80-year-old woman, had chronic renal failure related to renal amyloidosis. She had been treated by colchicine for 4 months. The second, a 75-year-old man with normal renal function, suffering from gout, was treated by colchicine for 3 weeks. Muscle biopsies displayed the same alterations, but the degree of severity was different. Conventional histology revealed vacuolar changes characterized by acid phosphatase-positive vacuoles and myofibrillar disarray foci. The lesions were selective for type I fibers. Ultrastructural study demonstrated autophagic vacuoles. Most of the vacuoles expressed dystrophin but not merosin. Several fibers reacted with anti-MHC class I antibody and granular deposits of membrane attack complex were observed on the surface of numerous myofibers. Anti-alphaB-crystallin antibody strongly reacted with vacuolar content. Physiopathologically, microtubules are primordial for vesicle movements and colchicine induces autophagic vacuole accumulation by preventing their fusion with lysosomes. The selective type I involvement is probably due to the higher tubulin amount in type I fibers. AlphaB-crystallin overexpression is related to its microtubule protection properties. Moreover, we suggest that vacuoles randomly floating in sarcoplasm might occasionally meet the plasma membrane and open in the extracellular space, leading to complement activation. Accurate diagnosis of colchicine myopathy is relevant because the treatment is based on colchicine interruption.

Aged↗

PubMed1984

Colchicine inhibition of insulin induction of stearoyl-CoA desaturase and fatty acid synthetase in cultured avian liver explants.

Chicken embryo liver explants cultured in chemically defined medium in the absence of serum provide a unique system to probe into the mechanism of insulin induction of lipogenic enzymes. Colchicine at concentrations of 0.2 and 1 microM in the culture medium caused inhibition of insulin induction of stearoyl-CoA desaturase and fatty acid synthetase by 50 and 90%, respectively. As measured by immunochemical techniques, the inhibition of the induction of these two enzyme systems resulted from the decreased content of the delta 9-terminal desaturase component of the stearoyl-CoA desaturase and the fatty acid synthetase. Colchicine, however, had no effect on the general protein synthesis, nor did it affect the malic enzyme, which is induced by triiodothyronine but not by insulin. Also, colchicine had no influence on the binding of 125I-insulin to isolated plasma membrane. Pretreatment of liver explants with insulin for 0.5-1 h and subsequent incubation in insulin-free media for 48 h resulted in induction of the desaturase and fatty acid synthetase. However, inclusion of colchicine in the media for 3 h subsequent to the treatment with insulin completely abolished the inductive effect of insulin, suggesting that colchicine affects events occurring subsequent to insulin binding to the cell surface membranes. Since lumicolchicine, an inactive isomer of colchicine, had no effect on insulin action, it is suggested that the inhibition of insulin induction of the desaturase and synthetase is related to the depolymerizing action of colchicine. Therefore, in eliciting long-term responses to insulin, microtubular integrity of the cell may be required for the transfer of a putative from cell surface insulin receptor to intracellular sites.

Animals↗

PubMed1992

Aging of tubulin at neutral pH: stabilization by colchicine and its analogues.

The effect of colchicine and its analogues, allocolchicine, 2,3,4-trimethoxy-4'-carbomethoxy-1,1'biphenyl, 2,3,4,4'-tetramethoxy-1,1'-biphenyl, 2,3,4-trimethoxy-4'-acetyl-1,1'-biphenyl, and tropolone methyl ether, on the aging process of tubulin has been examined. In contrast to the vinca alkaloid drugs which accelerate the formation of the paucidisperse 9 S polymers by a factor of 3.5, the colchicine class of ligands stabilize alpha,beta-tubulin. Less than 10% of the protein is transformed into the aggregates after 50 h of incubation in the presence of 1 x 10(-3) M colchicine, as compared to nearly 70-75% transformation in its absence. These results are supported by fluorescence examination of the retention of colchicine binding ability, as well as circular dichroism spectroscopy. In the presence of colchicine, the rate determining step is a conformational change, just as in its absence. The colchicine analogues which bind to tubulin in a rapidly reversible equilibrium were almost as effective in tubulin stabilization. Addition of vincristine to the system reduced the stability of the tubulin-colchicine complex. Furthermore, vincristine was found to have the same effects on the fresh complex as it does on pure tubulin; i.e., it induced the isodesmic linear polymerization and inhibited assembly into the microtubule-mimicking large polymers. This inhibition, however, was stoichiometric, whereas it is substoichiometric in the case of microtubules.

Animals↗

PubMed1984

The effect of colchicine treatment on the buoyant density of noradrenaline storage particles in the rabbit superior cervical ganglion.

The subcellular distribution of noradrenaline (NA) was studied in the rabbit superior cervical ganglion before and after colchicine treatment. One-third of the total NA could be sedimented with the microsomal material in control conditions. Upon colchicine treatment the percentage of the NA which was particle-bound increased only slightly. The absolute NA content of the superior cervical ganglion from colchicine-treated rabbits, however, showed a 3.5-fold increase compared to control animals. Density gradient centrifugation of the microsomal fraction revealed that the distribution of the NA-containing particles changed significantly. Before colchicine treatment the NA was found in a broad band covering the gradient fractions where 'light' and 'heavy' NA vesicles were expected to equilibrate. After colchicine treatment the NA was concentrated in the 'heavy' NA vesicles part of the gradient. The dopamine beta-hydroxylase activity and the NA content in the gradient are increased 3 times after colchicine treatment. These experimental results can be explained by the axoplasmic transport impairing action of colchicine. The neuronal cell body accumulates 'heavy' NA vesicles formed there, unable to transport them towards the periphery.

Animals↗

PubMed1986

Colchicine-induced granule cell loss in rat hippocampus: selective behavioral and histological alterations.

Bilateral injection of 3.5 micrograms of colchicine into two levels of the dentate gyrus produced a selective loss of dentate granule cells and persistent behavioral effects in male Fischer rats. Histological analysis confirmed that this dosage of colchicine resulted in the selective loss of most granule cells in both superior and inferior blades of the dentate gyrus near the injection sites, while sparing pyramidal cells in CA1, CA2, CA3, and CA4, and GABAergic interneurons throughout the hippocampus. Rats injected with colchicine were significantly more active than cerebrospinal fluid-injected controls 2, 7, 14, 21 and 28 days after treatment. Behavioral reactivity, assessed by the magnitude of the acoustic startle response and the latency to respond in a hot-plate test, was not affected at any of these time points. Retention of a step-through passive avoidance task was impaired in the colchicine group one month after surgery. Their step-through latencies were significantly shorter than control latencies, and they exhibited more partial entries during the retention test. Acquisition and performance in a radial-arm maze, measured up to 3 months after surgery, were also impaired by colchicine. Animals injected with colchicine required more trials to acquire the task and were less accurate in the task even after their performance had stabilized. These data suggest that the hippocampus modulates motor behavior and cognitive function. The results of these experiments also support the use of colchicine as a means of defining the functional and anatomical consequences following selective destruction of the granule cell population of the dentate gyrus.

Animals↗

PubMed1988

Effects of colchicine on the intraneuronal transport of secretory material prior to the axon: a morphofunctional study in hypothalamic neurosecretory neurons of the rat.

The effects of colchicine on neurosecretory neurons of the rat hypothalamus were studied by immunocytochemistry, high-resolution radioautography, and conventional electron microscopy. In control rats, intraneuronal immunocytochemical labeling of vasopressin, oxytocin and somatostatin occurred essentially in the Golgi apparatus, the neurosecretory granules and to a lesser extent, the endoplasmic reticulum. These immunostaining patterns were dramatically modified 24 h after the administration of colchicine: immunoreactive peptides were located in granular or tubular structures accumulated at the periphery of the perikarya, but the Golgi stacks were not immunostained. Two h after the administration of tritiated leucine, quantitative analysis of radioautographic labeling of supraoptic perikarya revealed large amounts of radioactive protein in the Golgi saccules of neurosecretory neurons in control rats, but in the neurons of colchicine-treated rats, radioautographic labeling was mainly located in granular structures accumulated at the periphery of the perikarya, with no significant labeling on the Golgi stacks. Lastly, 3 noteworthy effects of colchicine on the ultrastructural morphological features of these neurosecretory neurons consisted in: (1) a dramatic disorganization of the Golgi complexes, (2) an accumulation of electron-dense proteic material within the lumen of cisternae of both the rough and smooth endoplasmic reticulum and, (3) a marked depolymerization of perikaryal microtubules, specifically those associated with the Golgi stacks. Taken together, these data do not fit the prevailing concept that the colchicine-induced accumulation of secretory material within the perikarya of neurosecretory neurons essentially results from the blockade of axoplasmic transport mechanisms. Instead, they support the idea that the effects of colchicine are related to the inhibition of the intraneuronal transport of newly synthesized secretory material from the endoplasmic reticulum to the Golgi apparatus, suggesting that the microtubules associated with the Golgi stacks are possible sites of colchicine action.

Animals↗

PubMed1989

Inhibition of delayed hypersensitivity reactions in mice by colchicine. I. Mechanism of inhibition of contact sensitivity in vivo.

Colchicine has been recently shown to inhibit delayed hypersensitivity reactions (DHR). In the present study we investigated the effects of colchicine on contact sensitivity (CS) to dinitrofluorobenzene. Colchicine, at a dosage level of 15 micrograms/mouse, inhibited the elicitation of the contact response only when given on the day of ear challenge. Administration of the drug during the induction phase did not have any effect on the CS reaction. By using adoptive transfer experiments, we could demonstrate that CS was suppressed only when colchicine was given to the recipient mice, while treating the donors of immune lymph node cells (I-LNC) did not affect their ability to transfer a significant DHR. These findings were observed also when I-LNC were directly injected into the ears, a result which indicated that there was no effect of the drug on the ability of effector cells to migrate to the site of antigen challenge. Neither was there any effect on the distribution of T cell subsets in peripheral lymph nodes. The proliferative response of LNC to antigenic or mitogenic stimulation in vivo or in vitro was also not affected by colchicine pretreatment. These findings raise major questions about the mechanism of action of colchicine in vivo and suggest that more experimentation is required to probe the mechanism of colchicine-induced suppression of DHR.

Animals↗

PubMed1984

Inhibition of the acute ocular responses to nitrogen mustard by colchicine.

Colchicine, a naturally occurring alkaloid, inhibits both fast and slow axoplasmic transport by prevention of microtubule assembly. We have examined the influence of colchicine on the neurogenically mediated acute inflammatory responses to topically administered nitrogen mustard and formaldehyde on the albino rabbit eye. Topical administration of colchicine (10, 20 or 40 micrograms) once per day for 15 days inhibited the ocular hypertensive response, the leakage of protein into the anterior chamber, and the pupillary constriction observed following topical administration of nitrogen mustard. Colchicine pretreatment also inhibited the ocular hypertensive response to topically administered formaldehyde. Pretreatment of the eye with colchicine (20 micrograms day-1) for a period of 5 days proved to be ineffective in suppressing the ocular hypertensive effect of nitrogen mustard, while more prolonged pretreatment (10 or 15 days) significantly abrogated the characteristic injury responses. Topical administration of colchicine (20 and 40 micrograms) caused dilation of conjunctival and limbal vessels, but these vascular responses subsided as treatment continued. These preliminary experiments suggest that the inhibition of the ocular responses to nitrogen mustard by chronic colchicine pretreatment might be the result of modification of synthesis or release of sensory mediator(s).

Animals↗

PubMed1988

Evaluation of colchicine therapy in primary biliary cirrhosis.

We have conducted a double-blind controlled trial of colchicine in patients with primary biliary cirrhosis. Fifty-seven patients with biopsy-proven primary biliary cirrhosis were randomized to receive either 0.6 mg of colchicine twice daily or an identically appearing placebo. Patients underwent clinical and laboratory evaluation every 3 mo and liver biopsy annually. Differences in mean alkaline phosphatase and alanine aminotransferase values between the colchicine and placebo recipients were statistically significant at 4 yr. Differences in mean bilirubin and immunoglobulin M values, although lower in the colchicine group, did not reach statistical significance. In colchicine-treated patients, mean alkaline phosphatase values fell significantly compared with controls, from 281 to 112 IU/L (p less than 0.01). Similarly, mean alanine aminotransferase values fell significantly compared with controls, from 129 to 86 IU/L (p less than 0.05). Bilirubin values remained stable in drug-treated patients, even in those patients with initially elevated bilirubin values, whereas they nearly doubled in subjects receiving placebo. Although biochemical parameters of disease activity improved or stabilized in colchicine-treated subjects, no difference in histologic progression was detected between the two treatment groups. We conclude that colchicine is of clinical benefit to patients with primary biliary cirrhosis as judged by improvement in alkaline phosphatase and alanine aminotransferase activities as well as a tendency for stabilization of bilirubin values.

Alanine Transaminase↗

PubMed1991

The interaction of [13C]-enriched colchicine with tubulin as determined by NMR spectroscopy.

[13C]Colchicine, labeled at the tropolone ring methoxy carbon, was used to study interactions with tubulin containing either Mg2+ or Mn2+ at the high affinity divalent cation binding site. Similar experiments were carried out in the presence of excess free divalent cation. The results show that: (1) when Mn2+ occupies the N-site, the 13C signal of the colchicine methoxy carbon of protein-bound colchicine is not broadened, indicating that in protein-bound colchicine the tropolone methoxy group is not close to the N-site cation; (2) when excess Mn2+ is present in solution this 13C signal is severely broadened, indicating that a low affinity divalent cation site or the exchangeable site (E-site) divalent cation is situated near the colchicine binding site; and (3) in the absence of paramagnetic ions a downfield chemical shift is observed for the tropolone methoxy carbon of colchicine upon binding to tubulin, suggesting that colchicine binds near an aromatic group(s) on tubulin.

Animals↗

PubMed1987

Ligand-induced changes in the subcellular distribution of insulin receptors in rat liver: effects of colchicine.

The in vivo effects of colchicine on the subcellular distribution of insulin receptors have been studied in insulin-injected rats and in control animals. Colchicine (0.1 mg/100 g or 10 mg/100 g body weight, i.v.) did not affect the ability of plasma membranes and Golgi fractions of control rats to bind insulin. As previously reported (Desbuquois et al., 1982), the injection of native insulin (8 nmol, i.v.) caused a 50% decrease in the insulin binding activity of plasma membranes and a concomitant 50% increase in insulin binding to Golgi fractions. These changes occurred at 4 and 40 min after insulin injection but were no longer detectable at 3 h. Colchicine treatment did not affect the initial changes in the distribution of insulin receptors induced by insulin; however, in rats treated with the low dose of colchicine, insulin binding to plasma membranes at 3 h was not fully restored. Colchicine treatment did not alter the amount of acid-extractable insulin associated with Golgi fractions of insulin-injected rats. The time course of uptake of 125I-insulin was similar in plasma membranes, microsomal fraction and Golgi fractions of colchicine-treated (0.1 mg/100 g) and of untreated rats. These results suggest that colchicine does not interfere with the endocytosis of insulin receptors induced by their ligand and has little effect, if any, on the reinsertion of internalized receptors in the plasma membrane.

Animals↗