The effect of pH on rabbit atrial response to histamine

1976 ◽  
Vol 54 (2) ◽  
pp. 118-127 ◽  
Author(s):  
M. J. Hughes ◽  
I. A. Coret
Keyword(s):  
Histamine Receptor ◽  
Maximum Response ◽  
Force Of Contraction ◽  
Histamine Concentration ◽  
Adenyl Cyclase Activity ◽  
Chronotropic Response ◽  
Spontaneous Rate ◽  
Histamine Response ◽  
Ph Range ◽  
Rabbit Atria

The chronotropic response of isolated rabbit atria in normal Tyrode's medium increases monotonically with increasing doses of histamine (9 × 10−7–9 × 10−4 M). Plots of the inverse of response against the inverse of concentration were linear; and from these plots were derived values for the theoretical maximum response at 'infinite' dose and for the histamine concentration required to evoke a half maximum response. Alteration of pH by changing [HCO3−] at constant pCO2, [Na+] and osmolality did not appreciably affect the response to histamine in the range pH 7.0–7.6. However, at pH below 7.0 the magnitude of histamine response was reduced at all concentrations of histamine tested. In the pH range 7.0–7.6, additions of NaHCO3 at constant pCO2 increased the spontaneous rate of rabbit atria (in the absence of histamine); however, there was little effect of changing pH (in this range) by altering [HCO3−] at constant pCO2 when [Na+] and osmolality were kept constant. Immersion in solutions at pH's less than 7.0 led to decline in spontaneous rate and force of contraction. It is probable that depression of adenyl cyclase activity rather than a specific change in ionization of histamine receptor is responsible for a decreased response to histamine at pH 6.9.

Chronotropic response of spontaneously beating rabbit atria to hyperosmotic media

1977 ◽  
Vol 233 (2) ◽  
pp. H228-H233 ◽  
Author(s):  
L. A. Roberts ◽  
M. J. Hughes
Keyword(s):  
Rate Control ◽  
Passive Tension ◽  
Force Of Contraction ◽  
Tyrode Solution ◽  
Chronotropic Response ◽  
Wide Range ◽  
Osmotic Agent ◽  
Hyperosmolar Solutions ◽  
Rabbit Atria ◽  
Plateau Level

Spontaneously beating rabbit atria responded to hyperosmotic Tyrode bathing media with an increase in rate, force of contraction, and passive tension dependent on the level of osmolality and the osmotic agent employed. The positive chronotropic response reached a maximum within a few minutes and then declined to a lower, maintained plateau level. The plateau change in rate was similar whether the osmotic agent added to Tyrode solution was sucrose, mannitol or NaCl. For these agents, the response increased linearly with osmotic pressure of the bathing media from 300 to 500 mosmol/kg H2O, then progressively decreased approaching zero (plateau rate = control) at about 700 mosmol/kg H2O. The chronotropic response to urea in Tyrode solution, though less than for the other three agents, progressively increased over the entire range of osmolalities tested (from 300 to 700 mosmol/kg H2O). The inotropic response was positive for all agents from 300 to 600 mosmol/kg H2O. Passive tension of atria increased with added NaCl, sucrose, or mannitol, but not with urea. Propranolol did not alter the atrial response to hyperosmolality. Thus, we find that the chronotropic response of atria to hyperosmolar solutions is positive over a wide range of agents and osmolalities, in contrast to earlier reports of a direct negative chronotropic effect.

The characterization of cardiac histaminergic chronotropic receptors in the rabbit

1981 ◽  
Vol 59 (1) ◽  
pp. 14-18 ◽  
Author(s):  
Alicia Polanin ◽  
Thomas E. Tenner Jr. ◽  
John H. McNeill
Keyword(s):  
Histamine Receptor ◽  
Receptor Blockade ◽  
Chronotropic Response ◽  
Atrial Rate ◽  
Chronotropic Effects ◽  
Rabbit Atria ◽  
Stimulation Of

The effects of selective histamine receptor analogs were studied in spontaneously beating rabbit atria. Atrial rate was increased by histamine (an H1 and H2 agonist), 4-methylhistamine and impromidine (H2 agonists), and 2-pyridylethylamine (PEA, an H1 agonist). The responses to histamine, 4-methylhistamine, and impromidine were not affected by propranolol (1 × 10−7 M) or reserpine pretreatment. However, the response to PEA was nearly abolished upon pretreatment with propranolol or reserpine.Cimetidine pretreatment (H2 receptor blockade) competitively antagonised the positive chronotropic effects of histamine, 4-methylhistamine, and impromidine. Promethazine pretreatment (H1 receptor blockade) competitively blocked the chronotropic effects of histamine but had no effect on the responses to 4-methylhistamine or impromidine. These results suggest that stimulation of H1 and H2 receptors will cause a positive chronotropic response.

Intracellular calcium responses in CF/T43 cells: calcium pools and influx pathways

1997 ◽  
Vol 273 (2) ◽  
pp. L363-L373 ◽  
Author(s):  
R. A. Harris ◽  
D. J. Pon ◽  
S. Katz ◽  
J. W. Hanrahan
Keyword(s):  
Threshold Concentration ◽  
Epithelial Cell Line ◽  
Second Phase ◽  
Airway Epithelial ◽  
Histamine Concentration ◽  
Cyclic Monophosphate ◽  
Influx Pathways ◽  
Histamine Response ◽  
Second Peak ◽  
Initial Peak

We studied the intracellular free Ca2+ concentration ([Ca2+]i) response to histamine in a cystic fibrosis airway epithelial cell line (CF/T43). Histamine (100 microM; duration approximately 10 min) biphasically increased [Ca2+]i, with a rapid initial peak (30-45 s) followed by a smaller second peak that lasted for several minutes before returning to baseline. Neither peak specifically depended on Ca2+ influx. Exposure to bradykinin (10 microM) elicited a single peak that lasted 3-3.5 min before returning to baseline. Bradykinin increased intracellular inositol 1,4,5-trisphosphate (IP3), which peaked and returned to baseline within 150 s. Histamine also increased IP3 monophasically, but the peak was brief (< 20 s). Both phases of the Ca2+ response to histamine exhibited similar responsiveness to histamine concentration and sensitivity to antagonists. Cimetidine or thioperamide (1 mM) had no effect on the second peak. Pyrilamine blocked the second peak at concentrations similar to those required to block the initial peak. Activation of the second peak was observed at a threshold concentration of 1 microM comparable with the threshold of the initial peak. Neither adenosine 3',5'-cyclic monophosphate, guanosine 3',5'-cyclic monophosphate, nor cyclic ADP (cADP)-ribose altered the second phase of the histamine response.

Temperature and histamine receptor function—what is really happening?

1985 ◽  
Vol 63 (6) ◽  
pp. 751-755 ◽  
Author(s):  
D. A. Cook ◽  
C. A. Krueger ◽  
A. Michalchuk
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Low Temperatures ◽  
Histamine Receptor ◽  
Receptor Function ◽  
Guinea Pig Ileum ◽  
Abundant Evidence ◽  
Cast Doubt ◽  
Histamine Response ◽  
New Evidence

Early studies suggested that at low temperatures there was a transition of receptor type from an H1 to an H2 receptor when the temperature was reduced from 37 °C to temperatures below 20 °C. These original observations were based on the development of sensitivity of guinea-pig ileum to the H2 antagonist metiamide as the temperature was reduced. More recently, evidence from a number of laboratories has cast doubt on the existence of a simple H1–H2 receptor transition, but there is abundant evidence that there are major changes in the response of a variety of smooth muscle preparations to histamine at reduced temperatures. The evidence in regard to alterations in histamine response at low temperatures is reviewed, some new evidence presented, and a model which is consistent with most of the observations is suggested.

CONTRACTION OF THE RABBIT MAMMARY STRIP IN VITRO IN RESPONSE TO OXYTOCIN

1965 ◽  
Vol 48 (2) ◽  
pp. 186-198 ◽  
Author(s):  
Richard D. Moore ◽  
M. X. Zarrow
Keyword(s):  
Mechanism Of Action ◽  
Dose Response ◽  
Response Curve ◽  
Contractile Response ◽  
Post Partum ◽  
Mammary Glands ◽  
Contractile Force ◽  
Maximum Response ◽  
Force Of Contraction

ABSTRACT The isometric contractile response to oxytocin has been studied in vitro utilizing strips of tissue from rabbit mammary glands. Responses were maximal at resting tensions of 200–400 mg/mm2. The force of contraction increased from the beginning of lactation to about 9 days post partum and then leveled off. Little or no response is noted below 15° C and the maximum response is obtained in the range of 32 to36°C. Irreversible changes begin above 41° C. As little as 0.1 mU oxytocin/ml could be detected and the dose-response curve was demonstrated statistically to be linear between the dosages of 0.5 to 10 mU oxytocin/ml. The doseresponse curve reached a plateau at about 8–11 mU/ml. Replacing sodium with potassium resulted in a logarithmic decrease of contractile force with time. This decrease was partially reversible. The strip became inexcitable in calcium free Tyrode's solution. Excitability was again established by adding calcium. Other than to oxytocin, the mammary strip responded only to acetylcholine. The effect of acetylcholine could be blocked by atropine and this treatment did not affect the response to oxytocin. The site and mechanism of action of oxytocin are discussed.

Suppression of pulmonary and systemic vascular histamine H2-receptors in allergic sheep

1986 ◽  
Vol 60 (3) ◽  
pp. 791-797 ◽  
Author(s):  
T. Ahmed ◽  
M. King
Keyword(s):  
Vascular Resistance ◽  
Histamine Receptor ◽  
Base Line ◽  
Group 14 ◽  
H2 Antagonist ◽  
H2 Receptors ◽  
Pulmonary Arterial ◽  
Histamine Response ◽  
H1 Antagonist ◽  
Vasodepressor Response

We have previously demonstrated a depression of airway H2-receptor function in sheep allergic to Ascaris suum antigen. To investigate whether this is a generalized defect, we studied the H1- and H2- histamine receptor functions in the pulmonary and systemic circulations of allergic and nonallergic sheep. Pulmonary arterial pressure, and cardiac output were measured for calculation of pulmonary vascular resistance (PVR) and systemic vascular resistance (SVR) before and immediately after a rapid intrapulmonary infusion of histamine (10 micrograms/kg), with and without pretreatment with H1- (chlorpheniramine) and H2- (metiamide) antagonists. Histamine alone increased mean PVR to 435 and 401% of base line and decreased mean SVR by 51 and 54% in the nonallergic and allergic sheep, respectively (P less than 0.001). In the nonallergic sheep following pretreatment with chlorpheniramine (selective H2 stimulation) or metiamide (selective H1 stimulation), histamine decreased SVR by 18 and 36%, respectively, suggesting that approximately two-thirds of the vasodepressor response was mediated by H1-receptors and one-third by H2-receptors. Combined H1- and H2-antagonists completely blocked the histamine response. In allergic sheep the histamine-induced decrease in SVR was primarily mediated by H1-receptors, because the response was blocked by H1-antagonist, chlorpheniramine, and the H2-antagonist, metiamide, had no effect. In the pulmonary circulation selective H1-stimulation caused a similar increase in PVR in allergic (365%) and nonallergic sheep (424%), whereas selective H2-stimulation caused a significant decrease in PVR in the nonallergic group (14%) but not in the allergic group.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Analysis of Apparent Noncompetitive Responses to Competitive H1-Histamine Receptor Antagonists in Fluorescent Imaging Plate Reader-Based Calcium Assays

1999 ◽  
Vol 4 (5) ◽  
pp. 249-258 ◽  
Author(s):  
Thomas R. Miller ◽  
David G. Witte ◽  
Lynne M. Ireland ◽  
Chae Hee Kang ◽  
Jean M. Roch ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Histamine Receptor ◽  
Fluorescent Imaging ◽  
Model Systems ◽  
Imaging Plate ◽  
Transient Effects ◽  
Response Curves ◽  
Histamine Concentration ◽  
Pharmacological Characterization ◽  
Plate Reader

We have examined the utility of high throughput fluorescent imaging plate reader (FLIPR)-based calcium assays for pharmacological characterization of G-protein coupled receptors (GPCRs) using recombinant and native human H1-histamine receptors (H1-HR), expressed in HEK293 and HeLa S3 cells, respectively, as model systems. For stably transfected HEK293 cell lines, the potency of histamine for elevating intracellular calcium increased (pD2, 7.13 and 7.86) with increased H1-HR density (about 0.8 and 14 pmol/mg protein, respectively), though histamine binding affinities were similar. The classic H1-HR competitive antagonists diphenhydramine and chlorpheniramine appeared noncompetitive by causing depressions of the maximal histamine responses along with rightward shifts of histamine concentration-response curves, thus precluding Schild analysis. Applying the generalized Cheng-Prusoff equation to antagonist concentration-response curves for inhibition of fixed histamine concentrations yielded apparent pKb values that were consistent among recombinant and native receptors at different expression levels. These pKb values for diphenhydramine and chlorpheniramine (e.g., 7.83 and 8.77, respectively) were in good agreement with binding pKi values (e.g., 7.98 and 8.52, respectively). Apparent antagonist affinities determined from FLIPR calcium and competition binding assays were also consistent for the competitive antagonists mepyramine, tripelennamine, and promethazine. In phosphoinositide hydrolysis assays, chlorpheniramine exhibited insurmountable inhibition of histamine calcium responses, although to a lesser extent than that observed in calcium assays; pKb values were similar. These results demonstrate that competitive antagonist potencies can be attained from FLIPR-derived data by application of the generalized Cheng-Prusoff equation, despite apparent noncompetitive antagonism under these assay conditions. Apparent noncompetitive antagonist effects may in part be attributable to a lack of equilibrium of histamine and antagonists with H1-HR within the short duration of rapid transient effects of histamine on intracellular calcium.

scholarly journals Effects of Se deficiency on serum histamine concentration and the expression of histamine H2 receptor in the jejunum of chickens

2012 ◽  
Vol 15 (3) ◽  
pp. 547-552
Author(s):  
Guo-Qing Wang ◽  
Hong-Hai Wang ◽  
Hai-Xia Wang
Keyword(s):  
Histamine Receptor ◽  
Diet Group ◽  
Expression Level ◽  
Control Group ◽  
Histamine Concentration ◽  
Histamine H2 Receptor ◽  
H2 Receptor ◽  
Transmission Electron ◽  
Se Deficiency ◽  
Histamine Binding

Abstract The present study was designed to investigate the influence of Se deficiency on serum histamine concentration and the expression of histamine receptor in the jejunum of chickens. Forty neonatal chickens were randomly divided into two groups. Experimental chickens were fed a low-Se diet (0.034 mg/kg), whereas chickens in the control group were fed a diet with a Se level of 0.229 mg/kg. Ten chickens were sacrificed on days 30, 45, 60 and 75. Blood and jejunum samples were collected. Histamine concentration in the jejunum was measured by ELISA, the jejunal mast cell (MC) ultrastructure was studied by transmission electron microscopy, and the expression level of histamine H2 receptor (H2R) mRNA in the jejunum was examined using real-time PCR. Results: The jejunal histamine concentration in chickens fed the low-Se diet was significantly higher than that in the control group (P<0.01). Se deficiency induced degranulation of MC in the jejunum of chickens in the low-Se diet group; their cytoplasm was filled with fused granules and vacuoles. The expression level of jejunal H2R mRNA in chickens fed the low-Se diet was also significantly higher than that in the control group (P<0.01). The results obtained suggest that Se deficiency stimulates MC degranulation and release of histamine, binding H2R promotes both regulation of digestion and cell proliferation while protects the jejunum from injury induced by Se deficiency.

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