Predictors of COVID-19 vaccination hesitancy in China: a meta-analysis.

OBJECTIVES: This study aimed to examine predictors and moderators of COVID-19 vaccine hesitancy in Chinese cultural contexts. STUDY DESIGN: A meta-analysis and meta-regression analyses were conducted to examine the associations between predictors and vaccine hesitancy as well as moderators that may impact these associations. METHODS: We searched relevant articles from January 1, 2020, to May 12, 2022, in the databases of Web of Science, PubMed, ProQuest, ProQuest Dissertations & Theses Global and CNKI. Weighted average effect sizes (e.g., odds ratio) and 95% confidence intervals were computed in Comprehensive Meta-Analysis 3.0 using random-effects models. Heterogeneity tests were conducted prior to moderation analyses. RESULTS: Results from 161 studies in 73 published articles (N = 705,957) were meta-analyzed. Perceived risk of COVID-19 infection, health status, medical workers' recommendation, recommendations from family and friends, and vaccine coverage among relatives and friends were significantly associated with COVID-19 vaccine hesitancy in Chinese cultural contexts. Participant age, operationalization of vaccine hesitancy, and the time of each study exerted significant moderation effects. CONCLUSIONS: Both individual and relational factors influence vaccine hesitancy in Chinese cultural contexts Future vaccine promotion initiatives should focus on risk perceptions as well as influence from medical professionals, family and friends.

Levo-tetrahydropalmatine inhibits α4ß2 nicotinic receptor response to nicotine in cultured SH-EP1 cells.

Nicotine, a major component of tobacco, is highly addictive and acts on nicotinic acetylcholine receptors (nAChRs) to stimulate reward-associated circuits in the brain. It is well known that nAChRs play critical roles in mediating nicotine reward and addiction. Current FDA-approved medications for smoking cessation are the antidepressant bupropion and the nicotinic partial agonist varenicline, yet both are limited by adverse side effects and moderate efficacy. Thus, development of more efficacious medications with fewer side effects for nicotine addiction and smoking cessation is urgently needed. l-Tetrahydropalmatine (l-THP) is an active ingredient of the Chinese medicinal herb Corydalis ambigua that possesses rich neuropharmacological actions on dopamine (DA) receptors in the mesocorticolimbic dopaminergic reward pathway. L-THP has been explored as anti-addiction treatments for drug abuse including nicotine. However, the targets and mechanisms of l-THP-caused anti-nicotine effects are largely unknown. In this study we address this question by elucidating the effects of l-THP on human neuronal nAChRs using patch-clamp recordings. Human neuronal α4ß2-nAChRs were heterologously expressed in SH-EP1 human epithelial cells. Bath application of nicotine (0.1-100 µM) induced inward currents, co-application of l-THP (3 µM) inhibited nicotine-induced currents in the transfected cells. L-THP-caused inhibition was concentration-dependent (the EC50 values for inhibiting the peak and steady-state current were 18 and 2.1 µM, respectively) and non-competitive. Kinetic analysis of the whole-cell currents showed that l-THP slowed rising time and accelerated decay time constants. L-THP specifically modulated α4ß2-nAChRs, as it did not affect α7-nAChRs or α1*-nAChRs (muscle type). Interestingly, two putative α4ß2-nAChR isoforms, namely sazetidine A-activated, high-sensitive one (α42ß23-nAChR) and cytisine-activated, low-sensitive one (α43ß22-nAChR) were pharmacologically separated, and the low-sensitive one was more susceptible to l-THP inhibition than the high-sensitive one. In conclusion, we demonstrate that l-THP blocks neuronal α4ß2-nAChR function, which may underlie its inhibition on nicotine addiction.

Alternative polyadenylation events differ dramatically between Tongcheng and Large White pigs in response to PRRSV infection.

Alternative polyadenylation (APA) is a widespread post-transcriptional regulation mechanism that increases the biological complexity of transcriptome and proteome. However, it is unclear whether APA regulation plays a role in genetic resistance to porcine reproductive and respiratory syndrome virus (PRRSV). Here, we reported genome-wide APA regulation of porcine alveolar macrophages in PRRSV-resistant Tongcheng (TC) pigs and PRRSV-susceptible Large White (LW) pigs upon PRRSV infection. Using 3' mRNA sequencing strategy, we detected 75 981 high-quality APA sites in porcine alveolar macrophages of TC and LW pigs. Furthermore, 1202 and 1089 differentially expressed APA sites, as well as 79 and 117 untranslated region-APA switching genes were identified in TC pigs and LW pigs upon PRRSV infection respectively. The APA events in TC pigs and LW pigs were involved in different biological pathways, while APA events in TC pigs are directly associated with the immune response to PRRSV infection. In addition, we identified genetic variations affecting polyadenylation signal between TC pigs and LW pigs. These findings would provide helpful information on APA regulation for further understanding of genetic resistance to PRRSV.

Prevalence and factors associated with smoking among adults in Malaysia: Findings from the National Health and Morbidity Survey (NHMS) 2015.

INTRODUCTION: The continuous monitoring of smoking prevalence and its associated factors is an integral part of anti-smoking programmes and valuable for the evaluation of the effectiveness of anti-smoking measures and policies. This study aimed at determining prevalence of smoking and identifying socio-demographic factors associated with smoking among adults in Malaysia aged 15 years and over. METHODS: This is a cross-sectional study with a representative sample of 21 445 adults in Malaysia, aged 15 years and over, selected via a stratified, two-stage proportionate-to-size sampling method. Data were obtained from face-to-face interviews by trained research assistants, using a standard validated questionnaire. Multivariable logistic regression was performed to determine socio-demographic factors associated with smoking among Malaysians. RESULTS: The overall prevalence of smoking was 22.8% (95% CI: 21.9-23.8%), with males having a significantly higher prevalence compared to females (43.0%, 95% CI: 41.1-44.6 vs 1.4%, 95% CI: 1.1-1.7). The highest smoking prevalence was observed among other ethnicities (35.7%), those aged 25-44 years (59.3%), and low educational attainment (25.2%). Males, those with lower educational attainment and Malays were significantly associated with smoking. CONCLUSIONS: The prevalence of smoking among Malaysians, aged 15 years and over, remains high despite the implementation of several anti-smoking measures over the past decades. Specially tailored anti-smoking policies or measures, particularly targeting males, the Malays, younger adults and those with lower educational attainment, are greatly warranted to reduce the prevalence of smoking in Malaysia.

Evidence for a central role for electro-osmosis in fluid transport by corneal endothelium.

The mechanism of transepithelial fluid transport remains unclear. The prevailing explanation is that transport of electrolytes across cell membranes results in local concentration gradients and transcellular osmosis. However, when transporting fluid, the corneal endothelium spontaneously generates a locally circulating current of approximately 25 microA cm(-2), and we report here that electrical currents (0 to +/-15 microA cm(-2)) imposed across this layer induce fluid movements linear with the currents. As the imposed currents must be approximately 98% paracellular, the direction of induced fluid movements and the rapidity with which they follow current imposition (rise time < or =3 sec) is consistent with electro-osmosis driven by sodium movement across the paracellular pathway. The value of the coupling coefficient between current and fluid movements found here (2.37 +/- 0.11 microm cm(2) hr(-1) microA (-1), suggests that: 1) the local endothelial current accounts for spontaneous transendothelial fluid transport; 2) the fluid transported becomes isotonically equilibrated. Ca(++)-free solutions or endothelial damage eliminate the coupling, pointing to the cells and particularly their intercellular junctions as a main site of electro-osmosis. The polycation polylysine, which is expected to affect surface charges, reverses the direction of current-induced fluid movements. Fluid transport is proportional to the electrical resistance of the ambient medium. Taken together, the results suggest that electro-osmosis through the intercellular junctions is the primary process in a sequence of events that results in fluid transport across this preparation.

Autosomal dominant glut-1 deficiency syndrome and familial epilepsy.

Glut-1 deficiency syndrome was first described in 1991 as a sporadic clinical condition, later shown to be the result of haploinsufficiency. We now report a family with Glut-1 deficiency syndrome affecting 5 members over 3 generations. The syndrome behaves as an autosomal dominant condition. Affected family members manifested mild to severe seizures, developmental delay, ataxia, hypoglycorrhachia, and decreased erythrocyte 3-O-methyl-D-glucose uptake. Seizure frequency and severity were aggravated by fasting, and responded to a carbohydrate load. Glut-1 immunoreactivity in erythrocyte membranes was normal. A heterozygous R126H missense mutation was identified in the 3 patients available for testing, 2 brothers (Generation 3) and their mother (Generation 2). The sister and her father were clinically and genotypically normal. In vitro mutagenesis studies in Xenopus laevis oocytes demonstrated significant decreases in the transport of 3-O-methyl-D-glucose and dehydroascorbic acid. Xenopus oocyte membranes expressed high amounts of the R126H mutant Glut-1. Kinetic analysis indicated that replacement of arginine-126 by histidine in the mutant Glut-1 resulted in a lower Vmax. These studies demonstrate the pathogenicity of the R126H missense mutation and transmission of Glut-1 deficiency syndrome as an autosomal dominant trait.

Rabbit conjunctival epithelium transports fluid, and P2Y2(2) receptor agonists stimulate Cl(-) and fluid secretion.

Rabbit conjunctival epithelium exhibits UTP-dependent Cl(-) secretion into the tears. We investigated whether fluid secretion also takes place. Short-circuit current (I(sc)) was 14.9 +/- 1.4 microA/cm(2) (n = 16). Four P2Y(2) purinergic receptor agonists [UTP and the novel compounds INS365, INS306, and INS440 (Inspire Pharmaceuticals)] added apically (10 microM) resulted in temporary (approximately 30 min) I(sc) increases (88%, 66%, 57%, and 28%, respectively; n = 4 each). Importantly, the conjunctiva transported fluid from serosa to mucosa at a rate of 6.5 +/- 0.7 microl x h(-1) x cm(-2) (range 2.1--15.3, n = 20). Fluid transport was stimulated by mucosal additions of 10 microM: 1) UTP, from 7.4 +/- 2.3 to 10.7 +/- 3.3 microl x h(-1) x cm(-2), n = 5; and 2) INS365, from 6.3 +/- 1.0 to 9.8 +/- 2.5 microl. h(-1) x cm(-2), n = 5. Fluid transport was abolished by 1 mM ouabain (n = 5) and was drastically inhibited by 300 microM quinidine (from 6.4 +/- 1.2 to 3.6 +/- 1.0 microl x h(-1) x cm(-2), n = 4). We conclude that this epithelium secretes fluid actively and that P2Y(2) agonists stimulate both Cl(-) and fluid secretions.

Mercurial sensitivity of aquaporin 1 endofacial loop B residues.

The water channel protein aquaporin-1 (AQP1) has two asparagine-proline-alanine (NPA) repeats on loops B and E. From recent structural information, these loops are on opposite sides of the membrane and meet to form a pore. We replaced the mercury-sensitive residue cysteine 189 in AQP1 by serine to obtain a mercury-insensitive template (C189S). Subsequently, we substituted three consecutive cysteines for residues 71-73 near the first NPA repeat (76-78) in intracellular loop B, and investigated whether they were accessible to extracellular mercurials. AQP1 and its mutants were expressed in Xenopus laevis oocytes, and the osmotic permeability (P(f)) of the oocytes was determined. C189S had wild-type P(f) but was not sensitive to HgCl(2). Expression of all three C189S cysteine mutants resulted in increased P(f), and all three mutants regained mercurial sensitivity. These results, especially the inhibitions by the large mercurial p-chloromercunbenzene-sulfonic acid (pCMBS) ( approximately 6A wide), suggest that residues 71-73 at the pore are accessible to extracellular mercurials. A 30-ps molecular dynamics simulation (at 300 K) starting with crystallographic coordinates of AQP1 showed that the width of the pore bottleneck (between Connolly surfaces) can vary (w(avg) = 3.9 A, sigma = 0.75; hydrated AQP1). Thus, although the pore width would be > or = 6 A only for 0.0026 of the time, this might suffice for pCMBS to reach residues 71-73. Alternative explanations such as passage of pCMBS across the AQP1 tetramer center or other unspecified transmembrane pathways cannot be excluded.

Immunocytochemical localization of aquaporin-1 in bovine corneal endothelial cells and keratocytes.

For immunocytochemistry, cultured bovine corneal endothelial cells (CBCEC) and bovine corneal cryosections were utilized. Preparations were fixed, permeabilized, and incubated with primary rabbit anti-rat aquaporin 1 (AQP1) antibody followed by rhodamine-conjugated secondary antibody, and were counter-stained with Sytox nuclear acid stain. Confocal microscopy of CBCEC in the x, y, and z planes showed rhodamine fluorescence, indicating the presence of AQP1 antibody localized to the apical and basolateral domains of the plasma membrane, but not to the membranes of intracellular compartments or other subcellular locations. Preabsorption with control antigenic peptide yielded no positive staining. Similar results were obtained using freshly dissected bovine corneas; in addition, these images showed AQP1 distributed to the plasma membranes of keratocytes. No AQP1 staining was seen in corneal epithelium, and no staining was observed in CBCEC layers exposed to AQP3, AQP4, and AQP5 antibodies.

Corneal endothelial NKCC: molecular identification, location, and contribution to fluid transport.

Although Na(+)-K(+)-2Cl(-) cotransport has been demonstrated in cultured bovine corneal endothelial cells, its presence and role in the native tissue have been disputed. Using RT-PCR we have now identified a partial clone of the cotransporter protein in freshly dissected as well as in cultured corneal endothelial and epithelial cells. The deduced amino acid sequence of this protein segment is 99% identical to that of the bovine isoform (bNKCC1). [(3)H]bumetanide binding shows that the cotransporter sites are located in the basolateral membrane region at a density of 1.6 pmol/mg of protein, close to that in lung epithelium. Immunocytochemistry confirms the basolateral location of the cotransporter. We calculate the turnover rate of the cotransporter to be 83 s(-1). Transendothelial fluid transport, determined from deepithelialized rabbit corneal thickness measurements, is partially inhibited (30%) by bumetanide in a dose-dependent manner. Our results demonstrate that Na(+)-K(+)-2Cl(-) cotransporters are present in the basolateral domain of freshly dissected bovine corneal endothelial cells and contribute to fluid transport across corneal endothelial preparations.

Molecular identification and immunolocalization of the water channel protein aquaporin 1 in CBCECs.

PURPOSE: Water channel proteins are important pathways for water movements across cell membranes, including those in the corneal endothelium that contribute to the fluid transport mechanism essential in maintaining corneal transparency. This study was conducted to identify and locate the water channel protein(s) in cultured bovine corneal endothelial cells (CBCECs). METHODS: Poly(A)+ RNA was isolated from CBCECs, and MMLV reverse transcriptase and random hexamer primers were used to generate a cDNA pool by reverse transcription-polymerase chain reaction (RT-PCR). Two specific degenerate primers were synthesized based on consensus sequences from the major intrinsic lens protein superfamily; a "touchdown" PCR protocol accommodated the degeneracy. Immunolocalization was performed by incubating sections of CBCECs with an antibody against human aquaporin 1 (AQP1). Cryosections (0.85 microm) of CBCECs were used for light microscopy, and 800-A ultrathin cryosections were used for electron microscopy (EM). RESULTS: A 372-bp fragment was isolated. Its encoded amino acid sequence was 100% identical with that of bovine AQP1 (AQP2_bovin). CBCECs reacted strongly with the anti-AQP1 antibody, and the labeling was selectively localized to the plasma membrane by light microscopy. Subcellular localization by EM revealed immunoreactivity with the inner leaflets of the plasma membrane. CONCLUSIONS: The identity of the aquaporin, its abundance, and its membrane location suggest that it is a major pathway for fluid flow across endothelial cell membranes. This is consistent with transcellular endothelial fluid transport.

Transport of fluid by lens epithelium.

We report for the first time that cultured lens epithelial cell layers and rabbit lenses in vitro transport fluid. Layers of the alphaTN4 mouse cell line and bovine cell cultures were grown to confluence on permeable membrane inserts. Fluid movement across cultured layers and excised rabbit lenses was determined by volume clamp (37 degrees C). Cultured layers transported fluid from their basal to their apical sides against a pressure head of 3 cmH2O. Rates were (in microliter. h-1. cm-2) 3.3 +/- 0.3 for alphaTN4 cells (n = 27) and 4.7 +/- 1.0 for bovine layers (n = 6). Quinidine, a blocker of K+ channels, and p-chloromercuribenzenesulfonate and HgCl2, inhibitors of aquaporins, inhibited fluid transport. Rabbit lenses transported fluid from their anterior to their posterior sides against a 2.5-cmH2O pressure head at 10.3 +/- 0.62 microliter. h-1. lens-1 (n = 5) and along the same pressure head at 12.5 +/- 1.1 microliter. h-1. lens-1 (n = 6). We calculate that this flow could wash the lens extracellular space by convection about once every 2 h and therefore might contribute to lens homeostasis and transparency.

Cultured bovine corneal epithelial cells express a functional aquaporin water channel.

PURPOSE: Given recent physiological and in situ hybridization evidence for the presence of a water channel in corneal epithelium, this study was conducted to investigate its expression and characteristics using cultured bovine corneal epithelial cells (CBCEPCs). METHODS: CBCEPCs were grown in DMEM containing 2 ng/ml fibroblast growth factor and 6% fetal bovine serum. To determine their osmotic permeability (Pf), cells were passaged onto rectangular glass coverslips, and anisotonically induced volume changes were monitored by light scattering. To investigate expression, poly(A+) RNA from CBCEPCs was injected into Xenopus laevis oocytes, and the Pf of the oocytes was determined. RESULTS: For CBCEPCs challenged with a 10% hypotonic solution at 37 degrees C, the kinetic constant of volume change was k=0.52+/-0.04 seconds(-1), and the calculated Pf 72+/-6 microm/sec (n=16). The Pf of oocytes injected with water was 14+/-1.8 microm/sec (n=4); injection with poly(A+) RNA from CBCEPCs increased Pf to 77+/-6 microm/sec (n=6). This increase in Pf was inhibited by 72% (reduced to 22+/-1 microm/sec) by 0.3 mM HgCl2 and was inhibited by 56% to 58% by coinjection with aquaporin (AQP)5 antisense oligonucleotide. CONCLUSIONS: The comparatively high Pf determined for CBCEPCs, the presence of mRNA encoding water channels, and sensitivity to mercurial agents are typical of the expression of functional water channels. The predominant message is for AQP5, although the evidence was consistent with the presence of additional water channels. These findings bring renewed support for the notion that the epithelium can contribute to corneal hydration homeostasis.

Effects of ciprofloxacin, streptomycin, and gentamicin on rabbit corneal transendothelial electrical potential difference.

PURPOSE: A previous report suggested that high concentrations of ciprofloxacin in the anterior chamber may cause dose-dependent acute corneal decompensation. Therefore we evaluated the effect of varying concentrations of ciprofloxacin in the anterior chamber on the corneal endothelium and compared these effects with those of gentamicin and streptomycin. METHODS: We assessed endothelial transport function by determining transendothelial electrical potential differences (TEPDs) of rabbit corneas. Our control solution was bicarbonate-buffered balanced saline with glucose (BSG), to which we added ciprofloxacin (50, 100, 125, and 150 microg/ml), gentamicin (1,000 and 2,000 microg/ml), and streptomycin (196, 437, and 696 microg/ml). RESULTS: At high concentrations exceeding minimal inhibitory concentrations against 90% of common ocular isolates (MIC90), accelerated decay of TEPDs was seen with all three antibiotics. Adverse effects on TEPDs were noted at concentrations corresponding to >50 times MICs with ciprofloxacin and 40 x MICs with gentamicin, but only 2 times MICs with streptomycin. CONCLUSION: Our study shows that concentrations of ciprofloxacin, gentamicin, and streptomycin below or equal to their MIC90 levels do not adversely affect endothelial transport function in a rabbit model.

Sodium, potassium, two chloride cotransport in corneal endothelium: characterization and possible role in volume regulation and fluid transport.

PURPOSE: To search for membrane transporter proteins that could contribute to volume regulation and fluid transport by corneal endothelium. As an initial step, the authors have focused on Na+-K+-2Cl- cotransporters. METHODS: Bovine corneal endothelial cells were cultured to confluence. 86Rubidium was used as a tracer for K+ uptake determinations; uptake values were normalized per milligram of cell protein. RESULTS: Three components of K+ uptake were characterized: ouabain (1 mM) sensitive, bumetanide (0.1 mM) sensitive, and ouabain-bumetanide insensitive. Both the ouabain-sensitive and bumetanide-sensitive components increased in the presence of 26.2 mM HCO3-; 0.5 mM 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid abolished this increase. The bumetanide-sensitive component was completely inhibited in the absence of Na+ or Cl-. This component was increased 33% by a 33% hypertonic solution and was decreased 38% by a 33% hypotonic solution. The protein kinase C activator phorbol 12-myristate 13-acetate decreased the activity of the cotransporter, whereas forskolin, in the presence of isobutylmethylxanthine, decreased it. Calyculin A (100 nM), an inhibitor of phosphatases 1 and 2a, produced a large (97%) activation of this component. CONCLUSIONS: These results provided for the first time conclusive evidence for the presence of a Na+-K+-2Cl- cotransporter in corneal endothelium and of its possible involvement in volume-regulatory processes in these cells. Given the uptake values reported here, such cotransporter could contribute significantly to electrolyte transport and hence to fluid transport across this preparation.

Macular holes: migratory gaps and vitreous as obstacles to glial closure.

PURPOSE: Retinal glia may play an important role in the closure of macular holes. This in vitro study examines whether and how the specific pathoanatomy, including foveal eversion and foveal vitreous, may interfere with glial closure of macular holes. METHODS: Culture dishes used to grow glial cells were modified by the placement of slopes, vertical steps, and gaps to mimic the in vivo migratory surface in and surrounding macular holes. In separate experiments, defects were made in a rodent glial monolayer. These defects were exposed to hyaluronic acid (HA) and to rabbit (RV) and bovine (BV) vitreous gel. The migratory behavior and completeness of closure of defects were compared to controls. RESULTS: As expected, glial cells migrated further and in greater numbers on a smooth surface. Slopes and steps were moderate obstacles to migration; gaps in the surface were absolute obstacles. HA modified the pattern of adhesion of cells at the bottom of defects. Defects in the glial monolayer were repaired in 5-7 days. Compared to these controls, repair was inhibited by 11% (n.s.), 28% (P = 0.02), and 58% (P = 0.004) after direct exposure of defects to HA, RV and BV, respectively. CONCLUSION: The elevated and everted margins of macular holes represent slope, step, and gap-like obstacles to the migration of glial cells and hence to the healing of defects. The defect allows extension of extracellular matrix into it and the subretinal space. Our results indicate that gaps in the migratory surface caused and aggravated by eversion and the presence of vitreous present obstacles to glial migration and closure of macular holes.

A novel method to determine the diffusional water permeability of oocyte plasma membranes.

Measurements of the cell membrane diffusional water permeability (Pd) are important to characterize water passage across water channels and across the lipid bilayer component of the membrane. Existing methods for those measurements are involved; however, we report here a simple procedure to estimate Pd in Xenopus laevis oocytes and similar large cells. Due to the different densities of H2O and D2O (heavy water), an oocyte transferred from normal medium to a D2O-based medium floats initially, but subsequently sinks when a certain amount of the water originally in them is replaced by the D2O that diffuses in. We describe how the 'flotation time' (time that oocytes float in a heavy water solution before they start sinking) yields the Pd of the plasma membrane. Determination of Pd by this procedure and by the rate of tritiated water (T2O) efflux give for Pd results which are very close: 2.2 +/- 0.2 (n = 8) and 2.0 +/- 0.1 (n = 6) microns/s, respectively (T = 10 degrees C). Furthermore, our method detects the increase in Pd elicited in oocytes by either expression of water channel proteins, or by treating them with the pore-forming antibiotic amphotericin B. This method appears useful to gauge the expression and function of pore-forming, water-permeable membrane proteins.

Effects of acetylcholine, carbachol, and mannitol on rabbit corneal endothelial function as assessed by corneal deturgescence.

BACKGROUND: Anterior chamber miotic solutions are widely used in ophthalmic surgery to induce pupillary contraction. We investigated whether the acetylcholine, carbachol, or mannitol present in perfusing solutions can affect corneal endothelial function. METHODS: Freshly dissected deepithelized rabbit corneas were mounted in a Dikstein-Maurice chamber at 36 degrees C. The endothelial sides were perfused with six solutions: (A) 55 mM (1%) acetylcholine Cl plus modified balanced salts; (B) control for A, with acetylcholine Cl replaced by sucrose; (C) 0.55 mM (0.01%) carbachol Cl plus balanced salts; (D) balanced salts solution (BS; control for C); (E) 3% mannitol plus modified balanced salts; and (F) modified balanced salts (control for E, with mannitol replaced by sucrose). Corneal thickness was followed for 3 h in each experiment. The effect of solution E did not differ from that of solution F. RESULTS: The carbachol-containing solution produced a small increase in corneal thickness compared to the control solution, while the acetylcholine-containing solution resulted in corneal thickness lower than that in control preparations. CONCLUSION: From these data, acetylcholine is harmless to the endothelium, and may actually stimulate its fluid pump mechanism. Carbachol, on the other hand, appears to have a detrimental effect.