SEARCH · PubMed Health

Results for “Aqueous Humor”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12Linked to original sources

PubMed2000

Immunoregulation by aqueous humor.

PURPOSE: The eye is a classic example of an immune-privileged site. To investigate the local defense system of the eye, the immunosuppressive effects of the aqueous humor on cytokine production was examined. METHODS: Using T cell clones (TCCs) established from infiltrating cells in the aqueous humor of patients with human T lymphotropic virus type 1 (HTLV-1) uveitis as target cells and the aqueous humor of patients with senile cataract obtained during cataract surgery, we examined the effects of the aqueous humor on the production of cytokines by HTLV-1-infected TCCs. RESULTS: HTLV-1-infected TCCs produced large amounts of various cytokines. The aqueous humor inhibited the production of cytokines in a dose-dependent manner. The inhibitory activity was heat labile. First protein liquid chromatography showed at least four major peaks of different molecular size, indicating that the aqueous humor contains multiple immunosuppressive factors. Transforming growth factor-beta, alpha-melanocyte-stimulating hormone, and vasoactive intestinal peptide did not suppress cytokine production. The inhibitory activity was neutralized by monoclonal antibody to Fas ligand. CONCLUSION: These data suggest that soluble Fas ligand is a candidate suppressive factor in the aqueous humor.

Aqueous Humor↗

PubMed1991

Origin and renewal of the intrinsic glycoproteins of the aqueous humor.

Rabbits were injected either intravitreally or intra-aqueously with L-[3H]-fucose and killed at several intervals after the administration of this marker for glycoproteins. The aqueous humor, the vitreous body and the ciliary body were processed for radiometry (liquid scintillation counting), sodium dodecyl sulfate-poly-acrylamide gel electrophoresis (SDS-PAGE) and fluorography. Light microscopic autoradiography was carried out on semi-thin sections of the ciliary body and revealed intense activity in terms of the synthesis, migration and renewal of glycoproteins in the ciliary epithelium. The amount of unbound [3H]-fucose in the aqueous humor decreased sharply by 4 h, and the labeled glycoproteins were present only in very small quantities at 1 day after the intra-aqueous injection. When [3H]-fucose was injected intravitreally, unbound radiolabel could be detected in the aqueous humor for greater than 1 day and the labeled glycoproteins, for up to 21 days after injection. The amount of unbound or bound [3H]-fucose was higher in the vitreous than in the aqueous at any interval after the intravitreal injection. Following the intra-aqueous injection, the amount of label that reached the vitreous body was practically insignificant. The levels of radioactivity in the serum were extremely low, as they were in the contralateral eye when tritiated fucose was injected into one eye only. Most of the Coomassie blue-stained bands detected in SDS-PAGE contained labeled glycoproteins as revealed by fluorography of gels simultaneously containing aqueous and vitreous samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1998

Microbiological assay of ampicillin in serum and aqueous humor of patients given ampicillin-sulbactam injection.

The aim of this study was to determine the bacterial growth inhibitory activities of ampicillin in aqueous humor and serum of patients administered ampicillin-sulbactam combination intramuscularly prior to cataract surgery. 43 patients received a combination of both antibiotics intramuscularly at varying periods (60-140 minutes) prior to surgery. Aqueous humor and venous blood were collected at the beginning of the surgery. For microbiological assay, spores of Bacillus subtilis were incorporated in the agar. The test sample and the standard solutions (calibrators) of ampicillin and ampicillin-sulbactam combination were placed in 3 mm wells in the agar. The diameter zones of growth inhibitory activities of ampicillin of the calibrators and the test samples measured in mm were extrapolated to the standard curve and were recorded as ampicillin activity in micrograms/ml. The results of the assay were placed in 5 groups according to the time intervals between injection and collection of serum and aqueous humor (< or = 70, 75, 80, 90, > 90 minutes). Ampicillin activities in sera and aqueous humor of group 5 (> 90 minutes) were significantly higher than the others (p < 0.001). The ratio of ampicillin activities of sera and aqueous humor in group 5 patients was significantly lower indicating higher concentration of ampicillin activity in aqueous humor during this period. Bacterial growth inhibitory activities of ampicillin-sulbactam combination were adequate in aqueous humor of all patients with highest activity being 90 minutes after intramuscular administration indicating the potential usefulness of this antibiotic combination as chemoprophylaxis prior to cataract surgery.

Adult↗

PubMed1990

Effects of timolol on terbutaline- and VIP-stimulated aqueous humor flow in the cynomolgus monkey.

The effects of timolol on terbutaline- and VIP-stimulated aqueous humor flow were investigated in cynomolgus monkeys, with a labeled albumin dilution method. The maximal increase in aqueous humor flow caused by intracameral (100 micrograms/ml) or intravenous (0.4 micrograms/kg/min) administration of terbutaline was about 100%. The effect of intravenously infused terbutaline was completely abolished by intracameral administration of timolol, 0.1 mg/ml. The same dose of timolol also abolished the effect of intravenously infused VIP, 50 ng/kg/min. Intravenous administration of timolol, 0.2 mg/kg, had no effect on VIP-stimulated aqueous humor flow, when VIP (90 micrograms) was given intracamerally, but abolished completely the effect of intracameral terbutaline, 100 micrograms/ml. The results suggest that the effect of intravenously infused VIP on aqueous humor flow is secondary to activation of the sympathetic nervous system, while the effect of intracameral administration of VIP is a direct effect on the ciliary epithelium. The maximal aqueous humor flow achieved with terbutaline is comparable to that in conscious cynomolgus monkeys.

Animals↗

PubMed2004

Trabecular cell expression of fibronectin and MMP-3 is modulated by aqueous humor growth factors.

We investigated the mRNA and protein expression of fibronectin and stromelysin-1 (matrix metalloproteinase-3, MMP-3) by trabecular cells treated with growth factors present in primary and secondary aqueous humors. Serum-deprived trabecular cells were incubated for 48 hr or 7 days in medium containing either primary or secondary aqueous humor growth factors or in serum-free medium. We extracted total RNA, performed reverse transcription-polymerase chain reaction using primer pairs for fibronectin, stromelysin-1 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and quantified the products. We utilized Western blotting to detect and quantify fibronectin and stromelysin-1 protein. Compared to controls, expression of fibronectin mRNA by trabecular cells was increased by 50 and 100% after incubation in primary aqueous humor growth factors for 48 hr or 7 days, respectively, and 50 and 130% after incubation in secondary aqueous humor growth factors. Stromelysin-1 mRNA expression was decreased by 25 and 50% after incubation in primary aqueous humor growth factors for 48 hr or 7 days, respectively, and 80 and 85% after incubation for 48 hr or 7 days, respectively, in secondary aqueous humor growth factors. Fibronectin protein increased 3.5-fold and 6-fold after incubation for 48 hr with primary or secondary aqueous humor growth factors, respectively; after 7 days, the level increased 4- and 7-folds, respectively. Stromelysin-1 protein was not detectable by western blotting. The up-regulation of fibronectin mRNA by trabecular cells exposed to growth factors present in secondary aqueous humor augmented by the down-regulation of stromelysin-1 mRNA contributed to the accumulation of fibronectin. Our findings open the possibility that induction of stromelysin-1 gene expression in the trabecular meshwork of glaucomatous eyes could effectively reduce buildup of fibronectin in the aqueous outflow pathway to decrease outflow resistance in glaucomatous states of the eye.

Animals↗

PubMedDate not supplied

Corneal endothelial permeability and aqueous humor dynamics in normal pressure glaucoma.

Corneal endothelial permeability and aqueous humor dynamics were studied in 17 non-treated normal pressure glaucoma patients in order to analyse the relevance of these parameters in the pathophysiology of this disease. Corneal endothelial permeability and aqueous humor flow were measured by fluorophotometry and aqueous outflow facility was determined by tonography. The results were compared with those of 17 healthy controls of similar age. The mean corneal endothelial permeability values and the aqueous flow and outflow facility values of the patients did not differ significantly from those of the healthy controls (P = 0.8, P = 0.2 and P = 0.5, respectively). Normal pressure glaucoma does not affect the corneal endothelial permeability. The aqueous humor dynamics are not primarily involved in the pathophysiology of normal pressure glaucoma.

Adult↗

PubMed1985

Heat and protease treatment of aqueous humor: effect on cell DNA synthesis and growth.

Rabbit skin and Tenon's capsule fibroblasts were cultured in media containing 20% rabbit aqueous humor as a stimulatory agent. Cell stimulation was quantitated by 3H-thymidine uptake. The aqueous humor was either: (1) untreated; (2) heated at 37 degrees C for 60 min; (3) boiled for 2 min; or (4) heated at 37 degrees C for 60 min with 0.025% trypsin, followed by boiling. The effects of the various treatments of aqueous humor on cell stimulation were compared among themselves and to 10% fetal bovine serum. It was found that: (1) heating of aqueous humor at 37 degrees C for up to 60 min had no apparent effect on its ability to stimulate DNA synthesis in culture; (2) boiling and trypsin plus boiling reduced the ability of 20% aqueous humor to promote thymidine uptake to varying degrees; (3) 20% untreated aqueous humor was more effective than 10% fetal bovine serum in stimulating DNA synthesis in Tenon's capsule fibroblasts; skin fibroblasts responded similarly to both media.

Animals↗

PubMed2003

Increased interleukin-6 in aqueous humor of a patient with lung-metastatic intraocular adenocarcinoma.

PURPOSE: We report increased interleukin (IL)-6 level in aqueous humor of a case of lung adenocarcinoma with metastasis to iris and anterior chamber. DESIGN: Interventional case report. METHODS: In one case and 11 healthy cataract patients as controls, we checked the levels of IL-6, IL-2, and tumor necrosis factor (TNF)-alpha in aqueous humor and serum by enzyme-linked immunosorbent assay. RESULTS: Levels of these three cytokines in serum were almost the same as with the levels in aqueous humor in the control group. The IL-6 concentrations ranged from 12.6 to 27.0 pg/ml (mean, 23.5 pg/ml) in serum and 15.0 to 43.1 pg/ml (mean, 22.4 pg/ml) in aqueous humor. There was no statistically significant difference between them. Compared with the control, the IL-6 concentration in aqueous humor of this patient, 282.0 pg/ml, increased more than 10-fold. CONCLUSION: This is a report describing elevated IL-6 level in the aqueous humor of a patient with intraocular metastasis from lung adenocarcinoma.

Adenocarcinoma↗

PubMed1994

The effect of topical timolol on epinephrine-stimulated aqueous humor flow in sleeping humans.

PURPOSE: It has been shown that intravenously administered epinephrine can increase the rate of aqueous humor flow in sleeping humans. This experiment was conducted to determine if this stimulatory effect can be blocked by the beta-adrenergic antagonist timolol. METHODS: Twenty normal human subjects were studied for one sleep cycle at night. Epinephrine was infused intravenously at a rate of 1 microgram/min. One eye received a single drop of 0.25% timolol, and the fellow eye received a placebo. Aqueous humor flow was measured by the rate of disappearance of fluorescein from the eye. RESULTS: The rate of aqueous humor flow was 14% lower in the timolol-treated eye than in the placebo-treated eye during 6 hours of sleep. This difference was interpreted as being due to blockage of part of epinephrine's effect on aqueous humor flow by topical timolol. CONCLUSION: It was concluded that the effect of systemically administered epinephrine on aqueous humor flow is at least partly mediated locally on the eye and that some portion of timolol's well-known effect on daytime aqueous humor flow could be due to inhibition of the ocular effects of epinephrine.

Administration, Topical↗

PubMed2001

Transforming growth factor-beta 2 levels in aqueous humor of glaucomatous eyes.

PURPOSE: To determine whether clinical characteristics are correlated with increased levels of transforming growth factor-beta 2 (TGF-beta 2) in aqueous humor in glaucomatous eyes. METHODS: Aqueous humor samples were collected from 91 glaucomatous eyes. Included were samples from primary open-angle glaucoma (POAG) in 40 eyes, (pseudo)exfoliation syndrome (EXS) in 18 eyes, primary angle-closure glaucoma (PACG) in 26 eyes and uveitis-related secondary glaucoma (SG) in 7 eyes. TGF-beta 2 in aqueous humor was assessed with a specific-capture ELISA. RESULTS: The mean concentration (+/- standard error) of mature (biologically active) TGF-beta 2 in the aqueous humor of eyes with POAG was 293.6 +/- 33.6 pg/ml, significantly higher than that in eyes with PACG, EXS and SG: 147.5 +/- 28.1, 135.8 +/- 30.2 and 41.0 +/- 10.7 pg/ml, respectively (P = 0.0006, P = 0.0010 and P = 0.0003; analysis of variance). The mean concentration (+/- standard error) of total TGF-beta 2 in the aqueous humor of eyes with POAG was 1647.6 +/- 124.5 pg/ml, not significantly different from that in eyes with PACG, EXS and SG: 1482.9 +/- 148.2, 1442.7 +/- 187.8 and 1929.0 +/- 367.6 pg/ml, respectively. A multivariate analysis using logistic regression showed significant correlations between mature TGF-beta 2 concentration and history of cataract surgery (P = 0.0225) and the use of carbonic anhydrase inhibitors (P = 0.0143). CONCLUSIONS: Our results indicate that increased levels of TGF-beta 2 may play an important role in the pathogenesis of POAG.

Aged↗

PubMed1988

Aqueous humor flow measured with fluorophotometry in timolol-treated primates.

Anterior chamber aqueous humor flow rate was measured in unanesthetized owl monkeys using fluorophotometry and anterior chamber photogrammetry. The mean anterior chamber turnover constant (ko) was 0.01, the mean aqueous humor flow rate was 2.75 microliters min-1, and the mean anterior chamber volume was 317 microliters in 16 eyes of eight monkeys. A significantly lower (11%, P less than 0.002) flow rate was measured in the afternoon compared to flow rates measured in the morning. This diurnal cycle is analogous to the fluctuations in flow in humans and supports the hypothesis that aqueous humor formation in primates is regulated by endogenous mechanisms. To investigate the role of adrenergic mechanisms in regulating flow, the dose-response effect of topical timolol (0.5-100 micrograms) was measured. Five microliters drops were used to minimize systemic absorption. Lower concentrations (0.01% and 0.05%) caused sporadic changes in flow. Topical 0.1% timolol (5 micrograms) significantly decreased aqueous humor flow in the treated eye compared to baseline flow while flow in the contralateral eye was not significantly different from baseline flow. Higher concentrations of timolol (0.5% and 1%) caused a dose-related bilateral decrease in flow. These results indicate that even with small topical volumes systemic absorption of the higher concentrations of timolol occurs. Significant local inhibition of flow occurred following 5 micrograms of topical timolol whereas an equal bilateral decrease in flow occurred following a 100 microgram dose. These results suggest that the standard clinical dose (approximately equal to 100 micrograms) is supramaximal for decreasing aqueous flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗

PubMed1976

Computer-assisted instruction of current concepts in aqueous humor dynamics.

A portable intraocular pressure simulator faciliated teaching the concepts of aqueous humor formation and drainage. The values of input factors, such as facility of outflow, episcleral venous pressure, or uveoscleral outflow rate, were set by using dials on the front panel. The four computed outputs of the simulator-aqueous humor secretory rate, aqueous humor outflow rate, net filtration rate, and intraocular pressure-were displayed on individual meters.

Aqueous Humor↗

PubMed2003

Antioxidant status of dog aqueous humor after extracapsular lens extraction.

We determined the antioxidant status of the aqueous humor after extracapsular lens extraction in 14 mongrel dogs weighing about 10 kg. The animals were examined by slit lamp biomicroscopy, applanation tonometry and indirect ophthalmoscopy. One eye was submitted to conventional extracapsular lens extraction and the other was used as control. Samples of aqueous humor were obtained by anterior chamber paracentesis before and at days 1, 2, 3, 7 and 15 after surgery. Total antioxidant status was determined as the capacity of aqueous humor to inhibit free radical generation by 2,2-azobis(2-amidopropane) chlorine. Ascorbic acid concentration was measured by HPLC with UV detection. Protein content was determined with the biuret reagent. Statistical analysis was performed by ANOVA followed by the Tukey-Kramer test. Protein concentration increased from 0.61 to 22 mg/ml 24 h after surgery. These levels were maintained and returned to normal at day 7. Total antioxidant capacity was reduced from 50 to about 30 min until day 3 and at day 7 it was equal to control. Ascorbic acid levels were reduced from 252 to about 110 microM and then returned to control values at day 15. Considering the importance of ascorbic acid concentration in aqueous humor for the maintenance of the antioxidant status of the anterior segment of the eye, the decrease of antioxidant defenses suggests that the surgical procedures promote an oxidative stress condition in the eye.

Animals↗

PubMed1982

Effect of pilocarpine on aqueous humor formation in human beings.

The effect of pilocarpine on aqueous humor flow in the human eye was studied using fluorophotometry. Methods of measuring fluorescent intensity and of calculating aqueous humor flow were used that reduced the problem of uneven mixing of fluorescein, which is observed in the presence of miosis. The rate of aqueous humor flow through the anterior chamber of the placebo-treated eyes was 2.2 +/- 0.35 microL/min and of the pilocarpine, treated eyes was 2.5 +/- 0.47 microL/min. This increase in flow (14%) was statistically significant but too small to be clinically important. Pilocarpine was observed to reduce the anterior chamber volume of these subjects from 204 +/- 26 to 188 +/- 32 microL.

Adult↗

PubMed1998

[Residue of sodium hyaluronate in aqueous humor following intraocular lens implantation].

OBJECTIVE: To determine the residue of sodium hyaluronate in aqueous humor following intraocular lens (IOL) implantation. METHODS: The percentage concentration of sodium hyaluronate in aqueous humor in 23 patients (25 eyes) having undergone IOL implantation was measured by Shimadzu UV-3101 ultraviolet spectrophotometer before and after irrigation with BSS 2 ml, 5 ml and 8 ml. RESULTS: The different percentage concentrations of sodium hyaluronate were 65.50% +/- 18.12%, 10.20% +/- 4.80%, 2.19% +/- 1.83% and 0.70% +/- 0.91%. CONCLUSION: Replacement of aqueous humor by BSS 2 ml can eliminate the most part of sodium hyaluronate. Replacement of aqueous humor by BSS 8 ml can decrease the residue of sodium hyaluronate to trace amount and the postoperative intraocular pressure can maintain in normal range.

Aqueous Humor↗

PubMed1998

A small molecular weight factor in aqueous humor acts on C1q to prevent antibody-dependent complement activation.

PURPOSE: Aqueous humor inhibits activation of the classic complement pathway; however, the mechanism of this inhibition is unknown. We have examined at the molecular level potential factors responsible for the inhibition, and we have tried to determine where in the complement pathway the inhibition takes place. METHODS: Fresh rabbit aqueous humor was size fractionated by centrifuge concentrators and by size exclusion column chromatography, and each fraction was assayed for inhibition of the classic complement pathway in a standard CH50 hemolytic assay. Fractions with inhibitory activity were assayed for protein and the presence of ascorbic acid and were subjected to heat treatment. To identify where in the pathway the inhibitor(s) function, the expression of activated complement components bound to the surface of antibody-coated erythrocytes was analyzed by flow cytometry using fluorescein isothiocyanate-labeled antibodies to specific complement components. In addition, hemolytic assays were performed for the function of individual complement components. RESULTS: The most potent inhibition of the classic pathway was in a fraction of aqueous humor of less than 1.3 kDa. The inhibitory activity in the fraction was unassociated with detectable protein or ascorbic acid, and it remained present after heat treatment. The functional analysis through flow cytometry and hemolytic assays for individual complement components showed that the inhibitor in the less than 1.3-kDa fraction caused a blockade in the complement pathway at the level of C1q. CONCLUSIONS: The aqueous humor contains a unique potent anticomplementary factor that has a molecular weight less than 1.3 kDa. This heat-stable inhibitory factor inhibits the classic pathway at the level of C1q. These results imply that within the eye the complement pathway is inhibited at the earliest steps of its initiation. Such inhibition would prevent production of complement products that mediate inflammation and chemotaxis of inflammatory cells. Therefore, as part of the adaptation of immune privilege, the ocular microenvironment is protected from inflammation induced by antigen-antibody complexes.

Animals↗

PubMed1995

Superior cervical ganglionectomy in monkeys: aqueous humor dynamics and their responses to drugs.

The role of sympathetic innervation in regulating the responses of aqueous humor flow, outflow facility and pupillary diameter to timolol and epinephrine was investigated in cynomolgus monkeys following unilateral superior cervical ganglionectomy. Aqueous humor flow was measured fluorophotometrically under pentobarbital anesthesia before the first and after the ninth of twice-daily topical doses of epinephrine, and under ketamine anesthesia before the first and after the ninth of twice-daily topical doses of timolol, 4-19 months after denervation. Baseline aqueous humor flow rates determined 2-4 months following denervation were 40% greater under ketamine than under pentobarbital anesthesia, with no difference between denervated and control eyes. Epinephrine increased aqueous humor flow by up to 50% in a dose-dependent fashion in both eyes, with a non-significant tendency toward slightly greater potency and efficacy in the denervated eyes. Timolol decreased aqueous humor flow by up to 50% in a dose-dependent fashion with equal maximal efficacy in both eyes, but with slightly and statistically significantly greater potency and efficacy in the control eyes at submaximal doses. Early (1-3 months) but not late (23-27 months) after denervation, baseline pupil diameter under ketamine anesthesia was smaller in the denervated eyes than in the controls. The mydriatic response to 600 micrograms epinephrine was more sensitive in the denervated than the control eye both early (1-3 months) and later on (23-27 months) after denervation; timolol had no effect on pupil diameter in either eye. No striking differences in intraocular pressure or refraction were observed between the eyes under any of these conditions. Resting outflow facility or resistance and perfusion-induced facility increase or resistance reduction, measured by two-level constant pressure perfusion under pentobarbital anesthesia 1.5-4.5 years after unilateral sympathectomy, did not differ significantly between sympathectomized and control eyes. Facility increased (by up to 30-50% beyond washout) and resistance decreased (by up to 20-30% beyond washout) similarly in control and sympathectomized eyes 10-60 min and 3-4 hr after bolus intracameral epinephrine doses of 0.55 and 5.5 micrograms.

Animals↗

PubMed1997

Timolol decreases aqueous humor flow but not Na+ movement from plasma to aqueous.

PURPOSE: To determine whether the well-known effect of timolol in reducing ocular pressure and aqueous humor (AH) flow is a function of reduced Na+ movement from plasma to aqueous. Previously, the authors have shown this to be the case for carbonic anhydrase inhibitors. METHODS: The rate of appearance of 22Na in rabbit posterior aqueous was measured 1 to 3 minutes after the intravenous injection (time T) of the isotope. One hour before this, the animals received one of the following: two drops of 0.5% timolol, two drops of 3.5% pilocarpine, or 25 mg/kg intravenous methazolamide. At 1 minute (T + 1), a posterior chamber sample was taken; 2 minutes later (T + 3) a second sample was removed from the fellow eye. The rate constant of sodium accession is simply the difference between the two counts/2 minutes. Aqueous flow was measured by dilution of sulfacetamide marker as described previously. RESULTS: The rate constant (k(in)) for sodium entering the posterior chamber was 0.036 +/- 0.004 minute-1 (n = 17). Corresponding to previous findings, methazolamide (25 mg/kg intravenous) reduced this to 0.023 +/- 0.003 minute-1 (n = 14). Conversely, timolol (two drops of 0.5% solution) had no effect on kin, which measured 0.037 +/- 0.004 minute-1 (n = 12). Similarly, as expected, pilocarpine had no effect on k(in) (0.035 +/- 0.003 minute-1). Control flow was 3.9 microliters/minute +/- 0.4; after timolol, 2.5 microliters/minute +/-0.1; after methazolamide, 2.4 microliters/minute +/-0.2; after pilocarpine, 3.6 microliters/minute +/- 0.2. These are converted to rate constants by dividing by volume of posterior aqueous (60 microliters). The control rate constant for fluid entry was 0.065 minute-1, 1.8-fold higher than for sodium. CONCLUSIONS: A central dogma of the formation of AH (and cerebrospinal fluid) is that fluid moves isotonically from plasma to AH or cerebrospinal fluid and, therefore, that rate constant k(in) for fluid and for sodium are approximately the same. In the authors' hands, the fluid constant was modestly higher than for sodium. This holds for normal function and also for the reduced k(in) for fluid and sodium after carbonic anhydrase inhibition. The k(in) for neither flow nor sodium was affected by pilocarpine. Surprisingly, however timolol, which reduces flow, had no effect on Na+ entry.

Adrenergic beta-Antagonists↗