Control of the Coronary Circulation

Sparks, Harvey V.; Wangler, Roger D.; Dewitt, Donald F.

doi:10.1007/978-1-4613-0873-7_45

Cited by 2 publications

(3 citation statements)

References 183 publications

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“…How this is related to the pressure sensitivity of the K ÷ channel is not clear. It has been reported that prolonged ischemia is associated with cell swelling (Sparks, Wangler, and DeWitt, 1984). The mechanosensitive K + channels in the membrane of such cells may become active and further contribute to K ÷ loss.…”

Section: Physiological Significancementioning

confidence: 99%

A mechanosensitive K+ channel in heart cells. Activation by arachidonic acid.

Kim

1992

The Journal of General Physiology

133

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Mechanosensitive ion channels have been described in many types of cells. These channels are believed to transduce pressure signals into intracellular biochemical and physiological events. In this study, the patch-clamp technique was used to idendfy and characterize a mechanosensitive ion channel in rat atrial cells. In cell-attached patches, negative pressure in the pipette activated an ion channel in a pressure-dependent manner. The pressure to induce half-maximal activation was 12 -3 mmHg at +40 mV, and nearly full activation was observed at ~20 mmHg. The probability of opening was voltage dependent, with greater channel activity at depolarized potentials. The mechanosensitive channel was identical to the K + channel previously shown to be activated by arachidonic acid and other lipophilic compounds, as judged by the outwardly rectifying current-voltage relation, single channel amplitude, mean open time (1.4 +-. 0.3 ms), bursty openings, K + selectivity, insensitivity to any known organic inhibitors of ion channels, and pH sensitivity. In symmetrical 140 mM KC1, the slope conductance was 94 -+ 11 pS at +60 mV and 64 -8 pS at -60 mV. Anions and cations such as CI-, glutamate, Na +, Cs +, Li +, Ca 2+, and Ba 2+ were not permeant. Extracellular Ba ~+ (1 raM) blocked the inward K + current completely. GdCI3 (100 tiM) or CaCI2 (100 wM) did not alter the K + channel activity or amplitude. Lowering of intracellular pH increased the pressure sensitivity of the channel. The K + channel could be activated in the presence of 5 mM intracellular [ATP] or 10 IzM glybenclamide in inside-out patches. In the absence of ATP, when the ATP-sensitive K + channel was active, the mechanosensitire channel could further be activated by pressure, suggesting that they were two separate channels. The ATP-sensitive K + channel was not mechanosensitive. Pressure activated the K + channel in the presence of albumin, a fatty acid binding protein, suggesting that pressure and arachidonic acid activate the K + channel via separate pathways.

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Section: Physiological Significancementioning

confidence: 99%

A mechanosensitive K+ channel in heart cells. Activation by arachidonic acid.

Kim

1992

The Journal of General Physiology

133

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“…When discussing pathophysiology with second-year students, we point out the second. We ask medical students to learn about the coronary stenosis and reserve (16) during the second year in the context of the study of the pathophysiology of the cardiovascular system. This can be done using a graph showing coronary blood flow as a function of pressure downstream from a stenosis (Fig.…”

Section: Regulation Of Blood Flow In Specific Tissuesmentioning

confidence: 99%

“…However, increased flow velocity in distributing arteries causes local release of nitric oxide and vascular smooth muscle relaxation. The resulting small increase in diameter of distributing arteries is sufficient to prevent the drop in pressure, which would ordinarily accompany the increased flow associated with active hyperemia (16).…”

Section: A P S R E F R E S H E R C O U R S E R E P O R Tmentioning

confidence: 99%

Learning the regulation of peripheral blood flow.

Sparks

1999

Advances in Physiology Education

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Students can learn a great deal about the peripheral circulation when teaching is based on five building blocks: hemodynamic principles, neurohumoral control, and three elements of local control of blood flow (metabolic, myogenic, and paracrine). Study of a particular special circulation starts with the application of these building blocks in the context of the function of that tissue. For example, control of skin blood flow is largely concerned with regulation of body temperature (neurohumoral control) and the response to injury (paracrine control). Regulation of coronary blood flow is almost entirely a matter of meeting the metabolic needs of the myocardium (metabolic control). By mixing and matching the five building blocks and keeping in mind the special functions of a particular tissue, students can master the peripheral circulation efficiently.

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Control of the Coronary Circulation

Cited by 2 publications

References 183 publications

A mechanosensitive K+ channel in heart cells. Activation by arachidonic acid.

A mechanosensitive K+ channel in heart cells. Activation by arachidonic acid.

Learning the regulation of peripheral blood flow.

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