Peroxynitrite and nitric oxide differ in their effects  on pig coronary artery smooth muscle

Peroxynitrite generated in arteries from superoxide and nitric oxide (NO) may damage their function. Here, we compare the effects of peroxynitrite and peroxynitrite/NO-generating agents SIN-1 (3-morpholinosydnonimine hydrochloride), SNAP (S-nitroso- N-acetyl-penicillamine), SNP (sodium nitroprusside), and NONOate (spermine NONOate) on pig coronary artery. Deendothelialized artery rings were pretreated with these agents and then washed before examining their contractility. Pretreatment with all agents (200 μM) results in a decrease in the force of contraction in response to the sarco(endo)plasmic Ca2+ (SERCA) pump inhibitor cyclopiazonic acid (CPA): SNAP > NONOate ≥ peroxynitrite ≥ SIN-1 > SNP. Pretreatment with SNAP, NONOate, or SIN-1 also inhibits the force of contraction produced with 30 mM KCl, with SNAP being the most potent. Including catalase plus superoxide dismutase (SOD) during the preincubation has no effect. Including an NO scavenger [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide] or a guanylate cyclase inhibitor (1 H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) partially protects against SNAP. Pretreatment of cultured cells with peroxynitrite, but not with SNAP, inhibits the Ca2+transients produced in response to CPA. Pretreating isolated membrane vesicles with peroxynitrite inhibits the Ca2+ uptake due to the SERCA pump, with all the other agents being less effective. Thus peroxynitrite and NO both inhibit the CPA-induced contractions in deendothelialized artery rings, peroxynitrite by damage to the SERCA pump and NO possibly by a step downstream from the increase in cytosolic Ca2+.

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Peroxide resistance of ER Ca2+ pump in endothelium: implications to coronary artery function

AJP Cell Physiology ◽

10.1152/ajpcell.1997.273.4.c1250 ◽

1997 ◽

Vol 273 (4) ◽

pp. C1250-C1258 ◽

Cited By ~ 38

Author(s):

Ashok K. Grover ◽

Sue E. Samson

Keyword(s):

Endothelial Cells ◽

Smooth Muscle ◽

Coronary Artery ◽

Smooth Muscle Cells ◽

Cultured Cells ◽

Contractile Function ◽

Ischemia Reperfusion ◽

Muscle Cells ◽

Intact Cells ◽

Serca Pump

We examined the effects of peroxide on the sarco(endo)plasmic reticulum Ca2+ (SERCA) pump in pig coronary artery endothelium and smooth muscle at three organizational levels: Ca2+ transport in permeabilized cells, cytosolic Ca2+ concentration in intact cells, and contractile function of artery rings. We monitored the ATP-dependent, azide-insensitive, oxalate-stimulated45Ca2+uptake by saponin-permeabilized cultured cells. Low concentrations of peroxide inhibited the uptake less effectively in endothelium than in smooth muscle whether we added the peroxide directly to the Ca2+ uptake solution or treated intact cells with peroxide and washed them before the permeabilization. An acylphosphate formation assay confirmed the greater resistance of the SERCA pump in endothelial cells than in smooth muscle cells. Pretreating smooth muscle cells with 300 μM peroxide inhibited (by 77 ± 2%) the cyclopiazonic acid (CPA)-induced increase in cytosolic Ca2+ concentration in a Ca2+-free solution, but it did not affect the endothelial cells. Peroxide pretreatment inhibited the CPA-induced contraction in deendothelialized arteries with a 50% inhibitory concentration of 97 ± 13 μM, but up to 500 μM peroxide did not affect the endothelium-dependent, CPA-induced relaxation. Similarly, 500 μM peroxide inhibited the angiotensin-induced contractions in deendothelialized arteries by 93 ± 2%, but it inhibited the bradykinin-induced, endothelium-dependent relaxation by only 40 ± 13%. The greater resistance of the endothelium to reactive oxygen may be important during ischemia-reperfusion or in the postinfection immune response.

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Two mechanisms mediate relaxation by bradykinin of pig coronary artery: NO-dependent and -independent responses

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1991.261.3.h830 ◽

1991 ◽

Vol 261 (3) ◽

pp. H830-H835 ◽

Cited By ~ 13

Author(s):

C. L. Cowan ◽

R. A. Cohen

Keyword(s):

Nitric Oxide ◽

Methylene Blue ◽

Coronary Artery ◽

Thromboxane A2 ◽

Porcine Coronary Artery ◽

Cyclic Monophosphate ◽

Pig Coronary Artery ◽

Endothelium Dependent Relaxation

The role of nitric oxide and guanosine 3',5'-cyclic monophosphate (cGMP) accumulation in the endothelium-dependent relaxation of the porcine coronary artery to bradykinin was investigated by comparing relaxation and cGMP accumulation in the presence or absence of NG-monomethyl-L-arginine (L-NMMA) and methylene blue. Rings were treated with indomethacin to eliminate the effects of prostaglandins. Relaxation to bradykinin of rings contracted with the thromboxane A2 mimetic U-46619 was not affected by L-NMMA and was only minimally inhibited by methylene blue. Rings contracted with elevated potassium (25 mM) also relaxed completely to bradykinin. However, L-NMMA or methylene blue effectively inhibited relaxation to bradykinin in rings contracted with potassium. cGMP accumulation was stimulated by bradykinin and inhibited by L-NMMA or methylene blue in rings contracted with either U-46619 or potassium. These results suggest that in the absence of nitric oxide-induced cGMP accumulation, a nonprostanoid mechanism exists that is capable of completely relaxing U-46619-contracted coronary artery. This mechanism is either inhibited in or unable to relax potassium-contracted rings. These results also demonstrate that nitric oxide mediates the bradykinin-induced cGMP accumulation that is largely responsible for the relaxation during contraction with potassium.

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