Quantitative study of α-adrenergic receptors in circular and longitudinal muscle of isthmus of rabbit fallopian tube and in rabbit aorta

1977 ◽  
Vol 55 (5) ◽  
pp. 1102-1106
Author(s):  
K. Rajkumar ◽  
P. L. Sharma
Keyword(s):  
Fallopian Tube ◽  
Quantitative Study ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Rabbit Aorta ◽  
Practical Application ◽  
Human Fallopian Tube ◽  
Receptor Agonists And Antagonists

The affinity of phenylephrine (pD2 value) and KB value for phentolamine for the α-adrenergic receptors of circular and longitudinal muscle of isthmus of rabbit fallopian tube and rabbit aorta have been estimated. The affinity of both phenylephrine and phentolamine was significantly more for the α adrenoceptors of the longitudinal muscle of isthmus of rabbit fallopian tube and rabbit aorta than circular muscle of isthmus of fallopian tube.The results of this investigation suggest that α adrenoceptors of circular muscle of isthmus are atypical. If this holds good for the human fallopian tube, the development of selective α-adrenergic-receptor agonists and antagonists may be of potential practical application for the control of fertility.

Effects of some autonomic drugs on duodenal smooth muscle.

1979 ◽  
Vol 236 (1) ◽  
pp. E33
Author(s):  
S Anuras ◽  
D L Faulk ◽  
J Christensen
Keyword(s):  
Smooth Muscle ◽  
Adrenergic Receptors ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Adrenergic Agonists ◽  
Beta Adrenergic Receptors ◽  
Cholinergic Agonists ◽  
Beta Adrenergic ◽  
Alpha Adrenergic Receptors ◽  
Relative Potencies

Longitudinal muscle strips (LMS) and circular muscle strips (CMS), 2 mm wide and 1.5--2 cm long, from opossum duodenum were exposed to some autonomic agonists. The cholinergic agonists, acetylcholine, carbachol, methacholine, and bethanechol stimulated only tonic contractions in LMS and tonic followed by phasic contractions in CMS. These effects were abolished by atropine 10(-6) M. The ED50S of all cholinergic agonists for LMS were significantly lower than for CMS. Norepinephrine caused initial contraction (abolished by phenoxybenzamine, 10(-4) M), followed by relaxation (abolished by propranolol, 10(-5) M), and isopropylnorepinephrine caused relaxation (abolished by propranolol, 10(-5) M) in both layers. There were no differences in relative potencies for adrenergic agonists between the layers. Tetrodotoxin did not affect the response to adrenergic agonists. Thus, the potency of cholinergic agonists is greater in longitudinal than in circular muscle, and the layers respond differently to cholinergic agonists. The alpha-adrenergic receptors mediate contraction and beta-adrenergic receptors mediate relaxation on the duodenal smooth muscle.

Action of alpha 2A-adrenergic receptors in circular smooth muscle of canine proximal colon

1992 ◽  
Vol 262 (3) ◽  
pp. G517-G524 ◽  
Author(s):  
L. Zhang ◽  
K. D. Keef ◽  
M. E. Bradley ◽  
I. L. Buxton
Keyword(s):  
Smooth Muscle ◽  
Adenylate Cyclase ◽  
Binding Sites ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Receptor Agonist ◽  
Circular Muscle ◽  
Proximal Colon ◽  
Affinity Binding ◽  
Circular Smooth Muscle

Addition of the alpha 2-adrenergic receptor agonist clonidine (1 microM) to tetrodotoxin-treated strips of canine colonic circular smooth muscle resulted in a significant increase in contractile force that was blocked by addition of the alpha 2-antagonist yohimbine (0.1 microM). The alpha 2-receptor antagonist radioligand [3H]rauwolsine bound rapidly and reversibly to a single class of saturable sites (Bmax, 38.4 +/- 6.2 fmol/mg protein) in colonic circular smooth muscle membranes with an affinity (KD = 5.1 +/- 0.9 nM) characteristic of alpha 2-adrenergic receptors in smooth muscle. Studies in cells freshly isolated from circular muscle of canine proximal colon verified the smooth muscle origin of these receptors. Rank order of potency of alpha 2-adrenergic receptor antagonists in competition for [3H]rauwolsine binding was yohimbine greater than oxymetazoline much greater than prazosin. Affinity of alpha 2-receptors for yohimbine was indistinguishable from that of its optical isomer, rauwolsine, in both competition studies (KI = 3.4 nM) and in saturation-binding experiments employing [3H]yohimbine directly (KD = 4.2 nM). The alpha-receptor agonist epinephrine, in competition studies employing [3H]rauwolsine, revealed high-affinity binding sites that were converted to low-affinity binding sites for agonist by addition of 100 microM GTP gamma S. Addition of the alpha 2 more-selective agonist clonidine (100 microM) resulted in inhibition of adenylate cyclase activity that was abolished by pretreatment of tissue strips with pertussis toxin suggesting coupling of the alpha 2-receptor in colon to adenylate cyclase via the GTP-binding protein Gi. Our data demonstrate a physiological role for adenylate cyclase-coupled receptors of the alpha 2A-subtype in canine colon circular smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Menstrual cycle and sensitivity of human fallopian tube to prostaglandins

1986 ◽  
Vol 251 (6) ◽  
pp. R1126-R1136
Author(s):  
M. Nozaki ◽  
Y. Ito
Keyword(s):  
Fallopian Tube ◽  
Physiological Role ◽  
Circular Muscle ◽  
Slow Waves ◽  
Menstrual Cycles ◽  
Human Fallopian Tube ◽  
Low Concentrations ◽  
Endogenous Prostaglandins ◽  
Spontaneous Contractions ◽  
Human Oviduct

The shapes and frequencies of spontaneous contractions of circular muscle strips of the human oviduct differ during the menstrual cycles. However, under given conditions, the frequency and amplitude of the contractions were continuously reduced during perfusion with Krebs solution. In the presence of prostaglandin (PG) synthesis inhibitors or an antagonist, a gradual and continuous reduction was no longer observed, and low concentrations (10(-15)-10(-10) M) of PGE2 markedly suppressed the amplitude and frequency of the spontaneous contractions. The highest sensitivity of smooth muscle cells to PGE2 was observed during the periovulatory phases. Spontaneous prepotentials followed by slow waves were observed, and the latter potentials triggered contraction of the tissue. PGE2 (10(-14)-10(-12) M) inhibited, and PGF2 alpha (10(-9)-10(-7) M) enhanced the frequency of these slow waves. The amount of PGE series released from the tissues was twice of PGF series. These results suggest that endogenous prostaglandins play a physiological role in the transport of ovum in the human fallopian tube as a result of the regulation of spontaneous membrane and mechanical activities.

ENDOCRINE ACTIVITY OF THE HUMAN FALLOPIAN TUBE

1969 ◽  
Vol 61 (1_Suppl) ◽  
pp. S80 ◽  
Author(s):  
Hubertus A. van Leusden
Keyword(s):  
Fallopian Tube ◽  
Endocrine Activity ◽  
Human Fallopian Tube

Inhibition of Glutamatergic Synaptic Input to Spinal Lamina IIo Neurons by Presynaptic α2-Adrenergic Receptors

2002 ◽  
Vol 87 (4) ◽  
pp. 1938-1947 ◽  
Author(s):  
Yu-Zhen Pan ◽  
De-Pei Li ◽  
Hui-Lin Pan
Keyword(s):  
Receptor Antagonist ◽  
Synaptic Input ◽  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Dorsal Root ◽  
Primary Afferents ◽  
Noradrenergic System ◽  
Analgesic Action ◽  
Adrenergic Agonists ◽  
Excitatory Synaptic Input

Activation of spinal α2-adrenergic receptors by the descending noradrenergic system and α2-adrenergic agonists produces analgesia. However, the sites and mechanisms of the analgesic action of spinally administered α2-adrenergic receptor agonists such as clonidine are not fully known. The dorsal horn neurons in the outer zone of lamina II (lamina IIo) are important for processing nociceptive information from C-fiber primary afferents. In the present study, we tested a hypothesis that activation of presynaptic α2-adrenergic receptors by clonidine inhibits the excitatory synaptic input to lamina IIo neurons. Whole cell voltage-clamp recordings were performed on visualized lamina IIo neurons in the spinal cord slice of rats. The miniature excitatory postsynaptic currents (mEPSCs) were recorded in the presence of tetrodotoxin, bicuculline, and strychnine. The evoked EPSCs were obtained by electrical stimulation of the dorsal root entry zone or the attached dorsal root. Both mEPSCs and evoked EPSCs were abolished by application of 6-cyano-7-nitroquinoxaline-2,3-dione. Clonidine (10 μM) significantly decreased the frequency of mEPSCs from 5.8 ± 0.9 to 2.7 ± 0.6 Hz (means ± SE) without altering the amplitude and the decay time constant of mEPSCs in 25 of 27 lamina IIo neurons. Yohimbine (2 μM, an α2-adrenergic receptor antagonist), but not prazosin (2 μM, an α1-adrenergic receptor antagonist), blocked the inhibitory effect of clonidine on the mEPSCs. Clonidine (1–20 μM, n = 8) also significantly attenuated the peak amplitude of evoked EPSCs in a concentration-dependent manner. The effect of clonidine on evoked EPSCs was abolished in the presence of yohimbine ( n = 5). These data suggest that clonidine inhibits the excitatory synaptic input to lamina IIo neurons through activation of α2-adrenergic receptors located on the glutamatergic afferent terminals. Presynaptic inhibition of glutamate release from primary afferents onto lamina IIoneurons likely plays an important role in the analgesic action produced by activation of the descending noradrenergic system and α2-adrenergic agonists.

scholarly journals Role of beta-adrenergic receptor subtypes in pig uterus contractility with inflammation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Barbara Jana ◽  
Jarosław Całka
Keyword(s):  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Domestic Animals ◽  
Inhibitory Effect ◽  
Receptor Subtypes ◽  
Beta Adrenergic Receptor ◽  
Pharmacological Modulation ◽  
Uterine Inflammation ◽  
Myometrial Contractility

AbstractUterine inflammation is a very common and serious condition in domestic animals. To development and progression of this pathology often lead disturbances in myometrial contractility. Participation of β1-, β2- and β3-adrenergic receptors (ARs) in noradrenaline (NA)-influenced contractility of the pig inflamed uterus was studied. The gilts of SAL- and E.coli-treated groups were administered saline or E.coli suspension into the uterine horns, respectively. Laparotomy was only done in the CON group. Compared to the period before NA administration, this neurotransmitter reduced the tension, amplitude and frequency in uterine strips of the CON and SAL groups. In the E.coli group, NA decreased the amplitude and frequency, and these parameters were lower than in other groups. In the CON, SAL and E.coli groups, β1- and β3-ARs antagonists in more cases did not significantly change and partly eliminated NA inhibitory effect on amplitude and frequency, as compared to NA action alone. In turn, β2-ARs antagonist completely abolished NA relaxatory effect on these parameters in three groups. Summarizing, NA decreases the contractile amplitude and frequency of pig inflamed uterus via all β-ARs subtypes, however, β2-ARs have the greatest importance. Given this, pharmacological modulation of particular β-ARs subtypes can be used to increase inflamed uterus contractility.

scholarly journals Overexpression of beta-arrestin and beta-adrenergic receptor kinase augment desensitization of beta 2-adrenergic receptors.

1993 ◽  
Vol 268 (5) ◽  
pp. 3201-3208
Author(s):  
S. Pippig ◽  
S. Andexinger ◽  
K. Daniel ◽  
M. Puzicha ◽  
M.G. Caron ◽  
...  
Keyword(s):  
Adrenergic Receptors ◽  
Adrenergic Receptor ◽  
Receptor Kinase ◽  
Beta Adrenergic Receptor ◽  
Beta Adrenergic ◽  
Beta 2
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