Edward J. Barbieri

Glycine enhances the central depressant properties of ethanol in mice

The interaction between ethanol and glycine in the central nervous system was investigated in male Swiss-Webster mice. The loss of the righting reflex (LORR) was used as a measure of central nervous system depression. Mice were injected with ethanol (4.0 g/kg, IP), causing an ethanol-induced LORR. Immediately after the animals regained the righting reflex from ethanol administration, they received an intracerebroventricular (ICV) injection of saline or glycine (1, 15, 25, or 50 mumol/kg) in a volume of 5 microliters. Upon ICV injection of glycine, the mice lost the righting reflex once again. This effect of glycine in the presence of ethanol occurred rapidly and in a dose-dependent manner. Glycine induced a return to the LORR of 12.6 +/- 0.7, 24.5 +/- 1.3, 32.8 +/- 2.0, and 46.8 +/- 4.5 min when doses of 1, 15, 25, and 50 mumol/kg, respectively, were injected. D-Serine (15, 25, or 50 mumol/kg), an amino acid precursor of glycine, was injected (ICV) after the animals regained the righting reflex following ethanol injection (IP). Serine caused a return to the LORR of 0.5 +/- 0.5, 6.0 +/- 1.0, and 6.5 +/- 0.9 min when doses of 15, 25, and 50 mumol/kg, respectively, were injected. Strychnine was used to attenuate the ability of glycine and serine to cause a return to the LORR in the presence of ethanol. Strychnine, a competitive antagonist of glycine, significantly reduced the ability of glycine and serine to enhance the depressant action of ethanol.(ABSTRACT TRUNCATED AT 250 WORDS)

The presence of cocaine and benzoylecgonine in rat cerebrospinal fluid after the intravenous administration of cocaine.

Cocaine hydrochloride, in doses of 0.5, 1.0, 2.0 and 4.0 mg/kg, iv, was administered to male Sprague-Dawley rats. Cerebrospinal fluid (CSF) was collected from the cisterna magna over a 20 min period and blood samples were obtained at 20 min after cocaine administration. In addition, blood samples for the 1 mg/kg dose of cocaine were collected at 2, 10, 20 and 30 min following drug injection. Gas chromatography/mass spectrometry was used for the analysis of cocaine and its metabolites in plasma and CSF. The disappearance of cocaine (1 mg/kg) from the plasma exhibited first order kinetics with a half-life of 18.11 +/- 3.22 min. Cocaine and benzoylecgonine were found in CSF and the concentrations of cocaine and benzoylecgonine increased in CSF as the doses of cocaine were increased. CSF flow rates were not altered by the iv administration of cocaine or benzoylecgonine. The CSF-to-plasma ratios for cocaine were quite similar to each other over the dosage range of cocaine that was administered; however, the CSF-to-plasma ratios for benzoylecgonine decreased as the concentrations of benzoylecgonine increased in plasma and CSF. When benzoylecgonine (2 mg/kg, iv) was given, the compound was detected in CSF indicating that benzoylecgonine can enter into the central nervous system from the peripheral blood. This investigation shows that cocaine and benzoylecgonine can be assayed in CSF and that the plasma levels of these compounds correlate with their concentrations in CSF.

Effects of prostaglandins on vesicourethral smooth muscle of rabbit therapeutic implications

The effects of PGF 2-alpha and PGE2 on the vesicourethral smooth muscle of the rabbit were studied in vitro. PGF2-alpha had potent contractile effects on the bladder body and comparatively less in the bladder base and the proximal urethra. PGE2 contractile effects were two times greater than PGF 2-alpha on the bladder body but minimal or absent on the base and the urethra. The effects of PGF2-alpha and PGE2 seem to be mediated through a prostaglandin receptor as indicated by competitive antagonism of both prostaglandins by N-0164, a synthetic phenyl phosphonate. It also appears that the effects of PGF2-alpha PGE2 may not be mediated through muscarinic, adrenergic, nicotinic, or histaminic receptors or direct smooth-muscle action. The therapeutic implications of PGE2 in the patients with problems of bladder emptying are discussed.

Vesicourethral smooth muscle: Function and relation to structure

The effects of acetylcholine and norepinephrine on the longitudinal and circular smooth muscle strips from the rabbit bladder body, bladder base, and proximal urethra have been studied and compared. Based on the functional responses that were obtained, it was concluded that the vesicourethral structure can consist of three muscular systems. One system consists of the acetylcholine sensitive detrusor, the deep bladder base, and the longitudinal smooth muscle layer of the urethra. The second muscle system comprises the norepinephrine-sensitive detrusor muscle, the superficial bladder base, the bladder neck, and part of the longitudinal urethral smooth muscle. The third muscle system is the circular urethral musculature, unrelated to the detrusor circular muscle.

The accumulation and disappearance of cocaine and benzoylecgonine in rat hair following prolonged administration of cocaine

Hair samples were obtained at various time periods from male Sprague-Dawley rats following the injection of cocaine hydrochloride in doses of 5, 10, and 20 mg/kg, ip, for 28 days. Hair samples were also taken continually after the dosing was stopped until the presence of cocaine and benzoylecgonine were no longer detected in hair. Cocaine and benzoylecgonine in hair and plasma were analyzed by gas chromatography/mass spectrometry. Both cocaine and benzoylecgonine were found in hair samples 4 days after the initiation of cocaine administration. When cocaine dosing was stopped after 28 days, approximately 25 to 30 days were required for cocaine and benzoylecgonine to disappear from rat hair in the group of animals that received the highest dose of cocaine. The disappearance of cocaine and benzoylecgonine followed first-order kinetics. The mean rate constant and mean half-life for cocaine disappearance from hair were 0.212 +/- 0.005 day-1 and 3.31 +/- 0.09 days, respectively, and the mean rate constant and mean half-life for benzoylecgonine disappearance from hair were 0.098 +/- 0.006 day-1 and 6.90 +/- 0.28 days, respectively. The mean plasma concentrations of cocaine on Day 25 for the 5, 10, and 20 mg/kg doses of cocaine were 508 +/- 42, 852 +/- 95, and 2027 +/- 75 ng/mL, respectively, and the mean plasma benzoylecgonine levels for the 5, 10, and 20 mg/kg doses of cocaine were 49.9 +/- 7.0, 103.3 +/- 9.3, and 191.0 +/- 16.0 ng/mL, respectively. There was a positive correlation between the doses of cocaine hydrochloride administered and the plasma levels of both cocaine and benzoylecgonine. This study showed that cocaine and benzoylecgonine can be measured in rat hair following the administration of cocaine and that it was possible to correlate the concentrations of cocaine and benzoylecgonine found in hair with the doses of cocaine that were administered.

Effects of calcium and verapamil on vesicourethral smooth muscle of rabbits.

Isolated smooth muscle strips from the rabbit bladder body, bladder base, and proximal urethra were contracted with ionic calcium (Ca2+) alone and with the calcium-selective ionophore A23187, acetylcholine, norepinephrine, adenosine triphosphate (ATP), and direct electrical stimulation. The effects of Ca2+ and the calcium entry blocker verapamil on spontaneous muscle activity and on contractions induced by these agonists were examined. Ca2+ -free Tyrodes solution and verapamil, 1 x 10(-7)M and above, relaxed all of the vesicourethral smooth muscle strips. In addition verapamil, 1 x 10(-8) to 1 x 10(-6) M depending on the particular stimulant employed, noncompetitively inhibited smooth muscle contractions elicited by Ca2+, acetylcholine, norepinephrine, ATP, and direct electrical stimulation. It was concluded that transmembrane Ca2+ influx was important not only in the maintenance of tone and spontaneous phasic muscle activity, but also for the activation of contractions induced by all of the stimulants tested. The data also suggest that intracellular Ca2+ fraction(s) participate in the contractile responses to acetylcholine and norepinephrine challenge, but not to contractions evoked by ATP or electricity.

Effects of Substance P and Substance P Antagonists on Rat Salivary Secretion

The intra-arterial infusion of substance P produced dose-related responses of both parotid and submandibular salivary secretion in anesthetized rats. The substance P-induced secretion in both glands was inhibited by the substance P analogues [D-Arg 1, D-Trp7,9, Leu 11 ]-substance P and [D-Arg 1, D-Pro 2, D-Trp7,9, Leu 11 ]-substance P, but not by [D-Pro 2 , D-Trp7,9]-substance P. The profiles of protein and calcium levels obtained with substance P-induced salivary secretion for both glands were similar to those produced by acetylcholine stimulation and were not altered by the substance P analogues.

The effects of indomethacin and prostaglandins E2 and F2α on canine tracheal mucus generation

The effects of prostaglandins on respiratory smooth muscle are well known; however, their role in mucus generation has received little attention. This investigation was undertaken to study the actions of prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α) on secretion and synthesis of respiratory mucus glycoproteins. The method employed canine tracheal explants; radiochemical precursors were used in the culture media for labelling and quantitation of the secreted glycoproteins.Glycoprotein secretion was not significantly influenced by PGE2 (1×10−10 to 1×10−3M) or PGF2α (1×10−8 to 1×10−4M). However, PGF2α (1×10−3M and 1×10−2M), significantly stimulated glycoprotein secretion. The mechanism may have involved a contractile effect on myoepithelial cells of the submucosal glands. Synthesis of glycoproteins was significantly inhibited by PGF2α (1×10−5M), indomethacin (1×10−6M), and the combination PGF2α (1×10−5M)/indomethacin (1×10−6M). PGE2 (1×10−5M) and arachidonic acid (1×10−5M) were without effect. These data suggested that indomethacin inhibited glycoprotein synthesis by a mechanism other than an action on prostaglandin synthetase. In addition, because these agents inhibited synthesis of glycoproteins which were labeled with3H-glucosamine,35S-sulfate, and14C-serine, it appears that their action was primarily upon synthesis of the protein core.

In vitro study of antispasmodic effects of dicyclomine hydrochloride on vesicourethral smooth muscle of guinea pig and rabbit

Dicyclomine inhibition of acetylcholine-induced and barium chloride-induced isotonic contractions of the smooth muscle from three segments of the lower urinary tract (bladder body, bladder base, and proximal urethra) of the guinea pig and the rabbit was studied in vitro. In the guinea pig dicyclomine caused competitive inhibition of acetylcholine-induced contraction of the bladder body (1 x 10(-7) M to 1 x 10(-5) M) and the bladder base (1 x 10(-6) M, 1 X 10(-5) M) and was less potent than atropine and propantheline. In the rabbit significant blockade of acetylcholine-induced contractions occurred at dicyclomine concentrations of 5 x 10(-6) M to 3 x 10(-5) M in the bladder body and at 1 x 10(-5) M and 3 x 10(-5) M in the bladder base. In both species dicyclomine inhibitory effects were most marked in the bladder body, moderate in the bladder base, and minimal in the proximal urethra. Dicyclomine failed to cause inhibition of the barium chloride-induced contractions in the guinea pig vesicourethral smooth muscle. In rabbits, however, significant antagonism P less than 0.01) of barium chloride-induced muscle contraction was observed with dicyclomine at concentration 1 x 10(-5) M in both bladder body and the bladder base. The clinical implication of such properties of dicyclomine are discussed.

The calcium dependency of mucus glycoconjugate secretion by canine tracheal explants.

1 Canine tracheal explants, incubated overnight with [14C]‐glucosamine, elicited an enhanced secretion of ethanol‐precipitated 14C‐labelled glycoconjugate when challenged with methacholine, 10 μM. 2 Explants were rendered deficient in total calcium content and unresponsive to methacholine, 10 μM, by incubating them in calcium‐free medium for 18 to 22 h; however, the secretory response to the cholinergic agonist was restored with the addition of calcium to the medium. 3 A dose‐response relationship resulted when explants were challenged with methacholine in nutrient medium containing varied calcium concentrations (0.45 to 7.2 mM); alterations in the calcium concentration in the absence of methacholine had no significant effect on the basal secretion of 14C‐labelled glycoconjugate. 4 The calcium‐selective ionophore A23187, 10 μM, stimulated [14C]‐glycoconjugate secretion and induced the most significant effect in the presence of nutrient medium containing calcium. 5 Verapamil, 10 μM, a calcium‐entry blocker failed to inhibit basal or stimulated [14C]‐glycoconjugate secretion; however, the intracellular calcium antagonist TMB‐8, 10 to 100 μM, inhibited methacholine‐induced [14C]‐glycoconjugate secretion in a dose‐dependent manner. 6 These data suggest that respiratory mucus secretion is a calcium‐dependent process and that intracellular calcium is more vital than extracellular calcium in supporting this phenomenon.