Action of microelectrophoretic injection of mediators on single cells of the isolated guinea pig atrium

1970 ◽  
Vol 69 (1) ◽  
pp. 1-4
Author(s):  
I. S. Gushchin
Keyword(s):  
Guinea Pig ◽  
Single Cells ◽  
Guinea Pig Atrium

Relationship between potency of L-isoprenaline and β-adrenoceptor density estimated in single cells from tracheal smooth muscles of guinea pigs of different ages

1992 ◽  
Vol 70 (4) ◽  
pp. 458-461 ◽  
Author(s):  
Issei Takayanagi ◽  
Mitsutoshi Satoh ◽  
Noriko Kokubu ◽  
Teruko Kato
Keyword(s):  
Guinea Pig ◽  
Guinea Pigs ◽  
Dissociation Constants ◽  
Specific Binding ◽  
Single Cells ◽  
Regression Line ◽  
Smooth Muscles ◽  
Receptor Density ◽  
Age Related ◽  
Β Receptor

An age-related change in potency of L-isoprenaline in the presence of ascorbic acid, desmethylimipramine, corticosterone, pargyline, and phentolamine was obtained in tracheal strips from guinea pigs of differing ages between 6 and 40 weeks. The potency in the strips from 100-week-old guinea pigs did not significantly differ from that in strips from 40-week-old animals. Single cells were prepared from the tracheal muscles of 6-, 10-, 40-, and 100-week-old guinea pigs. The specific binding of [3H]dihydroalprenolol to the single cells was saturable. The dissociation constants of [3H]dihydroalprenolol were in good agreement with those of the membrane fractions from the guinea-pig tracheal muscles, and did not change with age. An excellent relationship between the potency of L-isoprenaline and the maximum binding of [3H]dihydroalprenolol estimated in the preparations from 6- to 40-week-old guinea pigs was found, suggesting that the increase in the potency of L-isoprenaline is due to the increase in the maximum binding or receptor density. The value in the preparations from 100-week-old guinea pigs deviated significantly from the regression line. This suggests the possibility that the decrease in potency in the strips from 100-week-old animals is due to a change in post β-receptor processes in responsiveness.Key words: guinea-pig trachea, single cells, β-receptor density, ageing, dissociation constant.

Ouabain uptake by endocytosis in isolated guinea pig atria

1988 ◽  
Vol 255 (4) ◽  
pp. C479-C485 ◽  
Author(s):  
H. Nunez-Duran ◽  
L. Riboni ◽  
E. Ubaldo ◽  
E. Kabela ◽  
L. Barcenas-Ruiz
Keyword(s):  
Electron Microscope ◽  
Guinea Pig ◽  
Mammalian Cells ◽  
Isometric Tension ◽  
Cardiac Cells ◽  
Inotropic Effect ◽  
Experimental Protocols ◽  
Guinea Pig Atrium ◽  
Endocytic Vesicles ◽  
Guinea Pig Atria

Mammalian cells specifically internalize some molecular species through receptor-mediated endocytosis (RME). We have used four different experimental protocols to investigate whether ouabain enters cardiac cells of guinea pig atrium through this pathway. First, by electron microscope morphometry we found that ouabain increased endocytic vesicles in atrial cells. Second, by scintillation counting we found that [3H]ouabain uptake by the tissue is decreased by three treatments that decrease RME, i.e., NH4Cl, trifluoperazine, and 16 mM [K+]0. Third, by radioautography at the electron microscope level, we checked that in preceding experiments [3H]ouabain was washed out of plasma membrane after 60-min rinse and interiorized into the cardiac cells. Fourth, isometric tension recordings showed that the positive inotropic effect of ouabain was diminished in the presence of inhibitors, whereas that of a hydrophobic analogue, ouabagenin, was not affected. These results suggest that ouabain enters cardiac cells through RME and also that an intracellular site may, at least in part, be responsible for its inotropic effect.

scholarly journals Calcium Exchange and Contraction Strength of Guinea Pig Atrium in Normal and Hypertonic Media

1969 ◽  
Vol 54 (4) ◽  
pp. 494-511 ◽  
Author(s):  
Gerald R. Little ◽  
William W. Sleator
Keyword(s):  
Steady State ◽  
Ion Exchange ◽  
Guinea Pig ◽  
Extracellular Space ◽  
Entry Rate ◽  
Steady State Condition ◽  
Peak Tension ◽  
Guinea Pig Atrium ◽  
Calcium Exchange ◽  
The Difference

A Krebs-Henseleit (KH) medium made hypertonic by adding nonpermeant molecules substantially increased the isometric peak tension at steady-state contractions below 3 per sec in guinea pig atrium at 27°C. Action potential durations were decreased. KH plus 100 mM raffinose or sucrose resulted in similar and nearly maximal changes which were essentially reversible upon return to normal KH. When one active contracting atrium was used to passively stretch a second atrium, the difference in Ca ion exchange (1 min exchange with the extracellular space) between active and stretched atria significantly increased at 1 per sec and at 2 per sec in going from normal to 100 mM hypertonic KH. The calculated mean Ca ion cellular exchange per beat per 100 g of cells (a) doubled in changing from normal to 100 mM hypertonic KH, and (b) decreased slightly in changing from contractions of 1 per sec to 2 per sec in normal KH. These data are consistent with the hypothesis (a) that Ca ion entry per beat from the extracellular space is proportional to membrane depolarized time with a constant medium and a steady-state condition, and the hypothesis (b) that 100 mM hypertonicity doubles the Ca ion entry rate during depolarization. These data enable rejection of the hypothesis that the peak tension is proportional to the Ca ion entry per beat from the extracellular space under steady-state conditions, and suggest that any additional Ca ion involved in the larger contractions at higher frequencies comes from an increase in Ca ion available from intracellular stores.

0N THE MECHANISM OF RELEASE OF H3-NORADRENALINE (H3-NA) FROM THE GUINEA-PIG ATRIUM BY THE CALCIUM IONOPHORE X5 37A

Abstracts ◽  
1977 ◽  
pp. 489
Author(s):  
A. G . Garcia ◽  
J. Gonzalez-Lopez ◽  
P. San-chez-Garcia ◽  
R. Pascual
Keyword(s):  
Guinea Pig ◽  
Calcium Ionophore ◽  
Guinea Pig Atrium

Delayed rectification in single cells isolated from guinea pig sinoatrial node

1992 ◽  
Vol 262 (3) ◽  
pp. H921-H925 ◽  
Author(s):  
J. M. Anumonwo ◽  
L. C. Freeman ◽  
W. M. Kwok ◽  
R. S. Kass
Keyword(s):  
Guinea Pig ◽  
Sinoatrial Node ◽  
Single Cells ◽  
Equilibrium Potential ◽  
Delayed Rectifier ◽  
Experimental Conditions ◽  
Whole Cell ◽  
Voltage Range ◽  
Whole Cell Patch Clamp ◽  
Delayed Rectification

We have studied delayed rectifier K+ currents (IK) in cells isolated from the sinoatrial node (SAN) region of the guinea pig. Using whole cell patch-clamp procedures, we measured the voltage dependence of IK activation and IK kinetics and the IK equilibrium potential in 4.8 mM extracellular K concentration solutions. Experiments were designed to contrast properties of guinea pig SAN IK with those of IK recorded from SAN cells of the rabbit. We find that guinea pig SAN IK differs from IK recorded from single rabbit SAN cells in its activation threshold, and in the absence of inactivation of whole cell currents recorded over a wide voltage range. These results, along with the relative insensitivity of guinea pig SAN IK to E-4031 and lanthanum, suggest that under our experimental conditions, a strongly rectifying IK component (IK,r) is not the major component of delayed rectification in the guinea pig SAN, as it appears to be in SAN cells of the rabbit.

Effects of Ca2+ and catecholamines on the guinea pig atrium action potential plateau

1977 ◽  
Vol 233 (2) ◽  
pp. H203-H210
Author(s):  
R. B. Robinson ◽  
W. W. Sleator
Keyword(s):  
Guinea Pig ◽  
Calcium Concentration ◽  
Potassium Conductance ◽  
Slow Inward Current ◽  
Activation Process ◽  
Action Potential Plateau ◽  
Guinea Pig Atrium ◽  
Opposing Effects ◽  
Guinea Pig Atria ◽  
External Calcium

The activation process in isolated electrically driven guinea pig atria was studied by means of simultaneous microelectrode and tension recording. Reducing external calcium from 2.5 to 1.25 mM prolonged the plateau but further reduction of calcium shortened it. Progressively increasing doses of the calcium antagonist D600 (up to 1.4 micrometer), however, monotonically decreased plateau duration. Either protocol monotonically decreased steady-state tension, but with markedly different effects on the restitution relation. Epinephrine, and to a lesser extent isoproterenol, restored plateau duration after exposure to either a calcium-free or D600-containing solution, but only the isoproterenol effect was propranolol sensitive. Addition of calcium chelators enhanced rather than prevented the effect of epinephrine on plateau duration in a calcium-free solution, extending the plateau duration to more than 3 times normal in some cases. These results are explained in terms of two opposing effects of a change in calcium concentration on plateau formation, one action being through the slow inward current and the second through a shift in a calcium dependence of the inward-rectifying, potassium conductance system.

Angiotensin II type 1 receptor mediates partially hyposmotic-induced increase of I Ks current in guinea pig atrium

2009 ◽  
Vol 458 (5) ◽  
pp. 837-849 ◽  
Author(s):  
Dimitar P. Zankov ◽  
Futoshi Toyoda ◽  
Mariko Omatsu-Kanbe ◽  
Hiroshi Matsuura ◽  
Minoru Horie
Keyword(s):  
Angiotensin Ii ◽  
Guinea Pig ◽  
Guinea Pig Atrium
Sign in / Sign up

Export Citation Format

Share Document