What question did this study set out to answer?

To examine the regulatory effects of protein kinase A and protein phosphatase inhibitors on calcium-activated potassium channels in colonic smooth muscle cells.

August 1, 1991AJP Cell Physiology

Regulation of Ca(2+)-activated K+ channels by protein kinase A and phosphatase inhibitors

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To examine the regulatory effects of protein kinase A and protein phosphatase inhibitors on calcium-activated potassium channels in colonic smooth muscle cells.
Recorded 260-pS calcium-activated potassium channel activity in excised inside-out membrane patches from dispersed canine proximal colon smooth muscle cells.
Tested channel response to 10 U/ml catalytic subunit protein kinase A in the presence and absence of ATP across various voltages and calcium concentrations.
Assessed channel open probability after adding protein phosphatase inhibitors, calyculin A and okadaic acid (10⁻⁹ to 10⁻⁶ M), with or without protein kinase A.
Protein kinase A increased channel open probability to 270 ± 48% of control (n=12) by shifting voltage-dependent activation by 13.9 ± 3.2 mV to more negative potentials (n=3), while omitting ATP eliminated this effect (n=3).
Co-application of okadaic acid or calyculin A with protein kinase A further elevated channel open probability by up to 250%, whereas calyculin A alone without protein kinase A had no effect.
Okadaic acid promoted greater channel opening than calyculin A, suggesting the endogenous phosphatase present in excised patches is distinct from types 1, 2A, or 2B.

Structured PICO

Population

Excised inside-out membrane patches from freshly dispersed smooth muscle cells of the canine proximal colon

Intervention

Catalytic subunit protein kinase A (10 U/ml) with or without phosphatase inhibitors (calyculin A and okadaic acid 10(-9) to 10(-6) M)

Comparator

Control (baseline channel activity), protein kinase A in the absence of ATP, or calyculin A in the absence of protein kinase A

Outcome

Open probability of 260-pS Ca(2+)-activated K+ channelssurrogate

Protein kinase A and endogenous phosphatases regulate the open probability of Ca(2+)-activated K+ channels in canine colonic smooth muscle cells.

Authors

ACA. CarlUniversity of Nevada, Reno JKJames L. KenyonUniversity of Vermont DUDaisuke UemuraKanagawa University

Discussion

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Implication

PKA-phosphatase regulation of KCa channels in canine colonic myocytes; extends basic mechanisms but leaves open human translation.

Cite This Study

Carl et al. (1991) studied this question.

synapsesocial.com/papers/6a83874ad71a93cd45e4e5dc https://doi.org/10.1152/ajpcell.1991.261.2.c387

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Regulation of Ca(2+)-activated K+ channels by protein kinase A and phosphatase inhibitors

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Regulation of Ca(2+)-activated K+ channels by protein kinase A and phosphatase inhibitors

Key Points

Structured PICO

Discussion

Implication

Cite This Study

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