Mechanism of slow discharges of sheep carotid artery.

Keatinge, W. R.

doi:10.1113/jphysiol.1978.sp012344

Cited by 14 publications

(13 citation statements)

References 43 publications

(39 reference statements)

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“…The observations made are in accord with those made on sheep carotid arteries (Keatinge, 1968(Keatinge, , 1978 and suggest that these arterioles, if they are close to the point of their origination from the middle cerebral artery (see Hill, Hirst, Silverberg & van Helden, 1986), possess two distinct inward calcium currents, an outward rectifying potassium current and a slow calcium-activated potassium current.…”

Section: Introductionsupporting

confidence: 84%

“…Properties of the slow after-hyperpolarization -effect of substituting barium for calcium As has been pointed out, action potentials recorded from middle cerebral arterioles were often followed by a slow after-hyperpolarization which was abolished by calcium removal and not detected at membrane potentials some 20-30 mV negative of rest (see also Keatinge, 1978). In voltage clamp experiments a small amplitude persistent outward current was occasionally detected following the larger membrane depolarizations (Fig.…”

Section: Effects Of Divalent Cations and Calcium Antagonistsmentioning

confidence: 63%

“…This indicates that these arterioles, like submucosal arterioles (Hirst & Neild, 1978) and sheep carotid arteries (Keatinge, 1978), show an anomalous rectification.…”

Section: Passive Electrical Propertiesmentioning

confidence: 92%

“…Action potentials have also been recorded from sheep carotid arteries (Keatinge, 1968(Keatinge, , 1978. These studies indicated that the voltage-dependent conductances activated by depolarization were complex.…”

Section: Introductionmentioning

confidence: 99%

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The action potential and underlying ionic currents in proximal rat middle cerebral arterioles.

Hirst¹,

Silverberg²,

Helden³

1986

The Journal of Physiology

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SUMMARY1. The active and passive electrical properties of isolated segments (length 120-220 jum, diameter 60-150 jim) of proximal rat middle cerebral arterioles (< 1 mm from parent artery) were analysed using a single-electrode current or voltage clamp.2. The voltage response to a current step exhibited an exponential time course. The mean resistance and time constant was 102 MQ and 265 ms corresponding to approximate specific resistance and capacitance of 60 kQ/cm and 4 #uF/cm2.3. Membrane resistance was constant in the range -55 to -80 mV. At potentials more negative than -80 mV there was a decrease in membrane resistance resulting in activation of an inward rectifier. At membrane potentials less negative than -50 mV the membrane resistance decreased; larger depolarizations ( >-40 mV) initiated small regenerative responses.4. External application of tetraethylammonium chloride caused membrane depolarization (10-15 mV), spontaneous discharge of action potentials and rhythmic arteriolar constriction. Action potentials studied with the membrane held at -60 mV had a large rapid depolarizing component, an after-depolarization and a small slower after-hyperpolarization.5. Tetrodotoxin (TTX) had no effect on the action potential. However, both the fast and slow components of the action potential were suppressed by extracellular removal of calcium ions and/or addition of cobalt ions, nifedipine or verapamil.6. Voltage-clamp studies demonstrated an inward rectifying current at membrane potentials more negative than -80 mV. At depolarized potentials at least four separate currents were activated; two separate calcium currents and two outward currents.

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Section: Introductionsupporting

confidence: 84%

Section: Effects Of Divalent Cations and Calcium Antagonistsmentioning

confidence: 63%

“…This indicates that these arterioles, like submucosal arterioles (Hirst & Neild, 1978) and sheep carotid arteries (Keatinge, 1978), show an anomalous rectification.…”

Section: Passive Electrical Propertiesmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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The action potential and underlying ionic currents in proximal rat middle cerebral arterioles.

Hirst¹,

Silverberg²,

Helden³

1986

The Journal of Physiology

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“…Recently Haeusler (1978), discussing the properties of the muscle membrane of the rabbit pulmonary artery, stated that TEA depolarizes the membrane presumably by suppression of K-conductance. Keatinge (1975Keatinge ( , 1978, studying the effect of procaine on the sheep carotid artery, found that spike generation in the presence of procaine is mainly due to depolarization of the membrane by suppression of K-permeability, and that these effects of procaine are still observed in Ca-free EGTA containing solution. He postulated that the spike generated from the carotid artery is due to activation of the Na-channel.…”

Section: Discussionmentioning

confidence: 99%

Actions of 4‐aminopyridine on Vascular Smooth Muscle Tissues of the Guinea‐pig

Hara

Kitamura

Kuriyama

1980

British J Pharmacology

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I Effects of 4-aminopyridine (4-AP) and procaine on the membrane and contractile properties of smooth muscle cells of the guinea-pig pulmonary artery and portal vein were observed. 2 The membrane potential and length constant of smooth muscle cells of the guinea-pig pulmonary artery were -53.2 mV and 1.2 mm, respectively, and those of the portal vein were -52.6 mV and 0.71 mm, respectively. The membrane was electrically quiescent in the pulmonary artery and it was electrically active in the portal vein. 3 Both 4-AP and procaine depolarized the membrane, increased the membrane resistance and suppressed the rectifying properties in both tissues. Both agents evoked a graded response from the muscle membranes of the pulmonary artery by outward current pulse. Procaine had a greater effect than 4-AP on the above membrane properties. The results suggest that 4-AP and procaine suppress K-conductance of the muscle membrane, and 4-AP but not procaine increases noradrenaline release from the nerve terminal. Presumably intracellular free Ca concentrations are also modified by these agents. The effects of 4-AP and procaine on the vascular muscle were compared with those on other excitable tissues.

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Neuromuscular transmission in intramural blood vessels

Hirst

1989

Comprehensive Physiology

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Mechanism of slow discharges of sheep carotid artery.

Cited by 14 publications

References 43 publications

The action potential and underlying ionic currents in proximal rat middle cerebral arterioles.

The action potential and underlying ionic currents in proximal rat middle cerebral arterioles.

Actions of 4‐aminopyridine on Vascular Smooth Muscle Tissues of the Guinea‐pig

Neuromuscular transmission in intramural blood vessels

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