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Full-Text Articles in Life Sciences
Signaling Mechanisms For Muscarinic Receptor-Mediated Coronary Vasoconstriction In Isolated Rat Hearts, Yi Zhang
Electronic Theses and Dissertations
The signaling mechanisms for muscarinic receptor-mediated vasoconstriction in coronary resistance arteries were studied in KCl-arrested isolated rat hearts perfused at a constant flow rate. The cholinergic agonists acetylcholine and bethanechol were given by bolus injection or constant infusion. The coronary vascular resistance was monitored by measuring the changes in perfusion pressure. The selective muscarinic agonist bethanechol caused a similar vasoconstrictor response as ACh, but with less potency and efficacy. Bolus injection of bethanechol evoked a phasic vasoconstriction in a dose-dependent manner, while infusion of bethanechol evoked a tonic vasoconstriction without producing tachyphylaxis. Coronary vascular responses to bethanechol were further examined …
Comparison Of Beta-Adrenoceptor Coupled Camp Production In Cultured Human Mononuclear Leukocytes And Myometrial Cells, Yu-Li Liu
Electronic Theses and Dissertations
$\beta\sb2$-Adrenoceptor ($\beta\sb2$-AR) agonists, such as terbutaline, are used as tocolytic agents in the treatment of preterm labor. $\beta$-Adrenoceptor stimulation relaxes myometrium through specific receptors coupled through Gs to adenylyl cyclase (AC) that catalyzes the conversion of ATP to cAMP. The purpose of this study was to compare $\beta$-adrenoceptors and cAMP production in cultured human leukocytes and myometrial cells, and to determine the importance of $\beta$-adrenoceptors and cAMP production in isoproterenol-induced myometrial relaxation. $\sp{125}$I-iodopindolol was used to assess $\beta$-adrenoceptor affinity and number cAMP levels were analyzed before and after stimulation by isoproterenol, AlF$\sb4\sp-$, forskolin, and PGE$\sb1$. Isometric recording was used to …
Persistent Oral Dyskinesias Induced By Long-Term Haloperidol Treatment Is Dissociated From Changes In Neostriatal B(Max) And Mrna Content For Dopamine D(2) Receptors, Nuoyu Huang
Electronic Theses and Dissertations
Due to the presumed associations of dopamine (DA) receptor supersensitivity phenomena in both long-term neuroleptic-treated tardive dyskinetic rats and neonatal 6-hydroxydopamine (n6-OHDA)-lesioned rats, we studied the influence of haloperidol on n6-OHDA-lesioned rats. At 3 days after birth rats received 6-OHDA-HBr (200 $\mu$g, bilateral intracerebroventricularly; desipramine pretreatment, 20 mg/kg, 1h) or vehicle. Two months later haloperidol (1.5/kg/day $\times$ 2 days/week for 4 weeks, then 1.5 mg/kg/day, every day for 10 months) was added to the drinking water. Spontaneous oral activity of intact and n6-OHDA-lesioned rats receiving haloperidol was reached and maintained at significantly higher levels after 15 weeks of haloperidol treatment. …
Indomethacin Reduces Splenic Red Pulp Macrophage Populations In Female New Zealand White Rabbits, Thane S. Thurmond
Indomethacin Reduces Splenic Red Pulp Macrophage Populations In Female New Zealand White Rabbits, Thane S. Thurmond
Electronic Theses and Dissertations
In an effort to elucidate the mechanism by which indomethacin (IN) attenuates the stimulatory effect of estradiol (E$\sb2$) on rabbit splenic red pulp macrophages (RPM), thirty-nine female New Zealand White rabbits were divided into 10 groups: ovariectomized (OVX), OVX/IN at 0.1 and 5.0 mg/kg body weight (bw)/day; sham OVX (SOVX), SOVX/IN at 0.1 and 5.0 mg/kg bw/day; OVX/25 mg E2, OVX/25 mg E$\sb2$/IN at 0.1 and 5.0 mg/kg bw/day; intact Control. Quantitative changes in RPM population in response to the treatments were measured using a 0 to 4 histologic grading scale. Estradiol treatment resulted in increased RPM grade when compared …
Denervation Supersensitivity Of The Rat Vas Deferens: A Role For Protein Kinase C, Sonny T. Abraham
Denervation Supersensitivity Of The Rat Vas Deferens: A Role For Protein Kinase C, Sonny T. Abraham
Electronic Theses and Dissertations
A role for protein kinase C (PKC) in the denervation-induced supersensitivity of the rat vas deferens was investigated. Chronic, surgical denervation of the rat vas deferens (up to 8 days) resulted in tissues that produced enhanced contractile responses to norepinephrine (NE) in isolated organ baths. Single challenges of NE (10 $\mu$M) produced 0.6 $\pm$ 0.1 g of maximal tension in the control vas whereas in the paired, denervated tissue 2.2 $\pm$ 0.3 g of tension was recorded (n = 6). Cumulative concentration-effect curves to NE produced in the denervated vas deferens were shifted 18-fold to the left of the control …
Differential Role Of The Endothelium In Regulating Microvascular Blood Flow, Tao Tang
Differential Role Of The Endothelium In Regulating Microvascular Blood Flow, Tao Tang
Electronic Theses and Dissertations
The vascular endothelial cell (EC) plays an important role in regulating vascular tone and local blood flow by sensing chemical and mechanical stimuli on the vascular wall and releasing a host of vasoactive substances upon activations of endogenous or exogenous vasoactive substances. The central hypothesis is that local control of blood now and autoregulatory behavior in the microcirculation is distinctive at different levels of the vasculature and is dependent on the cellular activities of the EC and its interaction with the local environment. The in vivo as well as the ex vivo, flow-controlled preparations of the hamster cheek pouch were …
Characterization Of The Vasoactivity Of Tachykinins In Isolated Rat Kidney: Functional Studies And In Vitro Receptor Autoradiography, Yuejin Chen
Electronic Theses and Dissertations
Although tachykinins have potent vascular actions, their effect on renal resistance blood vessels is currently unknown. The vasoactive properties of tachykinins and related analogs were assessed in isolated perfused rat kidney. At a basal perfusion pressure (PP) of 75 $\pm$ 6 mm Hg (n = 5), bolus injections of substance P (SP) had no significant vasoactive effect. Following a sustained increase in baseline PP (134 $\pm$ 10 mm Hg) produced by phenylephrine (1 $\mu$M), SP evoked a dose-dependent increase in PP. The largest dose of SP increased PP by 60 $\pm$ 5 mm Hg. The vasoconstrictor response to SP was …
Co-Sensitization Of Dopamine And Serotonin Receptors Occurs In The Absence Of A Change In The Dopamine D1 Receptor Complex After A Neonatal 6-Ohda Lesion, Li Gong
Electronic Theses and Dissertations
To test whether SKF 38393 could ontogenetically sensitize dopamine (DA) D$\sb1$ receptors and whether this sensitization would be associated with biochemical changes, intact and neonatal 6-hydroxydopamine (6-OHDA)-lesioned rats (200 $\mu$g i.c.v.) were treated daily from birth with SKF 38393 (3.0 mg/kg i.p. x 28 days) or its vehicle. In DA D$\sb1$ neonatally sensitized 6-OHDA rats, enhanced locomotor responses were observed with the first SKF 38393 challenge dose (3.0 mg/kg i.p.) at 6 weeks. This response increased further with weekly SKF 38393 treatments. Enhanced stereotyped behaviors were seen in both lesioned and sensitized rats at 8 weeks. There was no change …
Dopamine Agonists Modify The Development Of Brain D1 And D2 Receptor Responsiveness, Anwar A. Hamdi
Dopamine Agonists Modify The Development Of Brain D1 And D2 Receptor Responsiveness, Anwar A. Hamdi
Electronic Theses and Dissertations
Dopamine (DA) agonist-induced behavioral supersensitivity in the adult rat has served as the standard model for certain of the motor and behavioral side effects associated with long-term exposure to DA agonists in humans. The mechanisms relating receptor events with behavior mediation, however, remain unclear. The striatum of rats progresses through a prolonged and varied postnatal developmental period. In order to examine the relative contribution of D1 and D2 receptor-mediated mechanisms to behavioral changes which follow chronic dopamine agonist exposure, developing rats were treated daily from birth with a D1 agonist, SKF 38393 hydrochloride (3.0 mg/kg $\times$ 32d, i.p.), or a …
Dopamine Agonists Modify The Development Of Brain D1 And D2 Receptor Responsiveness, Anwar A. Hamdi
Dopamine Agonists Modify The Development Of Brain D1 And D2 Receptor Responsiveness, Anwar A. Hamdi
Electronic Theses and Dissertations
Dopamine (DA) agonist-induced behavioral supersensitivity in the adult rat has served as the standard model for certain of the motor and behavioral side effects associated with long-term exposure to DA agonists in humans. The mechanisms relating receptor events with behavior mediation, however, remain unclear. The striatum of rats progresses through a prolonged and varied postnatal developmental period. In order to examine the relative contribution of D1 and D2 receptor-mediated mechanisms to behavioral changes which follow chronic dopamine agonist exposure, developing rats were treated daily from birth with a D1 agonist, SKF 38393 hydrochloride (3.0 mg/kg $\times$ 32d, i.p.), or a …
Attenuation Of Antagonist-Induced Impairment Of Dopamine Receptors By L-Prolyl - L-Leucyl-Glycinamide, Mohamad I. Saleh
Attenuation Of Antagonist-Induced Impairment Of Dopamine Receptors By L-Prolyl - L-Leucyl-Glycinamide, Mohamad I. Saleh
Electronic Theses and Dissertations
It has been shown by others that the prenatal treatment of rats with haloperidol, a dopamine D2 receptor antagonist, leads to a permanent reduction in the number of striatal dopamine D2 receptors in adulthood. Conversely, postnatal treatment of lactating dams with haloperidol from birth for 21 days, leads to an increase in the number of striatal dopamine D2 receptors in the litters, when assessed as adults. The present study was undertaken in order to determine whether chronic, long-term postnatal challenge of rat pups per se, with specific dopamine D1 and D2 receptor antagonists, would modify the ontogeny of the respective …
Lung Paraquat Content And Effects On The Lung Glutathione Antioxidant System, Nadph, And Polyamines Resulting From Intravenous Coinfusion Of Paraquat And Putrescine To Rats, Jacob R. Dunbar
Electronic Theses and Dissertations
Paraquat was administered to male, Sprague-Dawley rats via continous infusion, at dosage rates of 250 (LoPQ) or 500 (HiPQ) nmoles/hr for seven days. The purpose was to characterize the effects of prolonged, low blood levels of the herbicide on selected lung biochemical parameters. The efficacy of putrescine as an inhibitor of pulmonary paraquat accumulation, in vivo, was assessed in these animals by I.V. coinfusion of 2500 or 5000 nmoles putrescine/hr. Dose-dependent levels of both paraquat and putrescine were achieved by 18 hours and were maintained throughout the exposure period. Terminal lung paraquat content was also dose-dependent and up to 18-fold …
Cisplatin Ototoxicity In The Guinea Pig: An Electrophysiological, Morphological, And Biochemical Study, Sarah E. Barron
Cisplatin Ototoxicity In The Guinea Pig: An Electrophysiological, Morphological, And Biochemical Study, Sarah E. Barron
Electronic Theses and Dissertations
The purpose of this study was to determine changes induced by cisplatin on hair cell (HC) morphology, compound action potential (CAP), Preyer reflex (PR), and Na,K-ATPase activity in the cochlear lateral wall. Guinea pigs were treated with either 0.42, 0.83, 1.17, 1.50 mg/kg cisplatin, i.p. or sterile water for 12 consecutive days and tested on day 13. HC condition was visualized with scanning electron microscopy (SEM), CAP was initiated with a 1 volt click, and Na,K-ATPase activity was measured by the method of Fiske and SubbaRow. HC damage was linear with dose and occurred throughout the turns of the cochlea …
Failure Of Opioids To Modify Noradrenergic Neuronal Recovery From A Dorsal Bundle Lesion In Neonatal Rats, Ellen L. Kunkel-Bagden
Failure Of Opioids To Modify Noradrenergic Neuronal Recovery From A Dorsal Bundle Lesion In Neonatal Rats, Ellen L. Kunkel-Bagden
Electronic Theses and Dissertations
Morphine and exogenous opioid peptides alter the development of central noradrenergic neurons damaged by neonatal treatment with the neurotoxin 6-hydroxydopa. Transection of the dorsal noradrenergic bundle (DNB) in neonatal rats produces nearly the same alteration in the developmental pattern. It was of interest to determine whether morphine or an exogenous opioid peptide (metenkephalin) was able to modify the recovery of noradrenergic neurons after neonatal surgical transection of the DNB. Neonatal rats were divided into two groups. Both groups received saline (0.85%) or naloxone (2.0 mg/kg) by the intraperitoneal (i.p.) route. In the first group the animals received an additional i.p. …
Enantiomeric Influences In Neuroleptic Binding To Models Of The Dopamine Receptor, Timothy A. Robert
Enantiomeric Influences In Neuroleptic Binding To Models Of The Dopamine Receptor, Timothy A. Robert
Electronic Theses and Dissertations
No abstract provided.