Analysis of pulmonary and systemic vascular responses to cromakalim, an activator of K+ATP channels

1991 ◽  
Vol 260 (3) ◽  
pp. H957-H966 ◽  
Author(s):  
R. K. Minkes ◽  
P. Kvamme ◽  
T. R. Higuera ◽  
B. D. Nossaman ◽  
P. J. Kadowitz

Cardiovascular and pulmonary responses to cromakalim, a member of a novel class of antihypertensive agents that open ATP-sensitive K+ (K+ATP) channels, were investigated in the anesthetized cat. Intravenous injections of cromakalim in doses of 30-300 micrograms/kg decreased arterial pressure (AP), pulmonary arterial pressure (PAP), and increased cardiac output (CO), while producing small changes in right and left atrial pressures. Pulmonary and systemic vascular resistances were decreased and vasodilator responses to cromakalim were blocked by glybenclamide, a K+ATP channel-blocking agent. The low dose of cromakalim caused a reflex increase in heart rate (HR) and right ventricular contractile force (RVCF), whereas the high dose decreased HR and RVCF. Under constant-flow conditions the K+ATP channel opener caused dose-dependent decreases in hindquarters perfusion pressure, and when tone was elevated in the pulmonary vascular bed, dose-dependent decreases in pulmonary lobar arterial perfusion pressure. Hindquarters and pulmonary lobar vasodilator responses to cromakalim were inhibited in a specific manner by glybenclamide. The present data show that cromakalim has significant vasodilator activity in both the systemic and pulmonary vascular beds and suggest that responses to this agent result from activation of glybenclamide-sensitive K+ATP channels. These data show that cromakalim can cause substantial decreases in systemic and pulmonary vascular resistance in a dose that has little effect on RVCF.

2004 ◽  
Vol 96 (2) ◽  
pp. 455-462 ◽  
Author(s):  
B. D. Nossaman ◽  
P. A. Dabisch ◽  
J. T. Liles ◽  
S. R. Baber ◽  
H. C. Champion ◽  
...  

The effects of peroxynitrite (ONOO-) on vascular responses were investigated in the systemic and hindquarters vascular bed and in the isolated perfused rat lung. Intravenous injections of ONOO- decreased systemic arterial pressure, and injections of ONOO- into the hindquarters decreased perfusion pressure in a dose-related manner. Injections of ONOO- into the lung perfusion circuit increased pulmonary arterial perfusion pressure. Responses to ONOO- were rapid in onset, short in duration, and repeatable without exhibiting tachyphylaxis. Repeated injections of ONOO- did not alter systemic, hindquarters, or pulmonary responses to endothelium-dependent vasodilators or other vasoactive agonists and did not alter the hypoxic pulmonary vasoconstrictor response. Injections of sodium nitrate or nitrite or decomposed ONOO- had little effect on vascular pressures. Pulmonary and hindquarters responses to ONOO- were not altered by a cyclooxygenase inhibitor in a dose that attenuated responses to arachidonic acid. These results demonstrate that ONOO- has significant pulmonary vasoconstrictor, systemic vasodepressor, and vasodilator activity; that short-term repeated exposure does impair vascular responsiveness; and that responses to ONOO- are not dependent on cyclooxygenase product release.


2013 ◽  
Vol 305 (9) ◽  
pp. H1288-H1296 ◽  
Author(s):  
Edward A. Pankey ◽  
Supat Thammasiboon ◽  
George F. Lasker ◽  
Syed Baber ◽  
Joseph A. Lasky ◽  
...  

Cardiovascular responses to the tyrosine kinase inhibitor imatinib were investigated in the rat. Intravenous injections of 0.3–30 mg/kg imatinib produced small decreases in pulmonary arterial pressure, larger dose-dependent decreases in systemic arterial pressure, and no change or small increases in cardiac output, suggesting that the systemic vasodilator response is more pronounced under baseline conditions. When pulmonary arterial pressure was increased with U-46619 or Nω-nitro-l-arginine methyl ester (l-NAME), intravenous injections of imatinib produced larger dose-dependent decreases in pulmonary arterial pressure. Imatinib attenuated the acute hypoxic pulmonary vasoconstrictor response. Vasodilator responses to imatinib were not inhibited by meclofenamate, glybenclamide, or rolipram, suggesting that cyclooxygenase, ATP-sensitive K+(KATP) channels, and cAMP were not involved in mediating the response. In a 21-day prevention study, imatinib treatment (50 mg/kg ip) attenuated the increase in pulmonary arterial pressure, right ventricular hypertrophy, and small vessel remodeling induced by monocrotaline. Imatinib reduced PDGF receptor phosphorylation and PDGF-stimulated thymidine incorporation in rat pulmonary artery smooth muscle cells. These data suggest that the beneficial effect of imatinib in pulmonary hypertension may involve inhibition of PDGF tyrosine kinase receptor-mediated effects on smooth muscle cell proliferation and on vasoconstrictor tone. These results indicate that imatinib has nonselective vasodilator activity in the pulmonary and systemic vascular beds similar to the Rho kinase inhibitor fasudil and the calcium entry antagonist isradipine. The present results are consistent with the hypothesis that imatinib may inhibit a constitutively active tyrosine kinase vasoconstrictor pathway in the pulmonary and systemic vascular beds in the rat.


1992 ◽  
Vol 262 (3) ◽  
pp. H852-H861
Author(s):  
R. K. Minkes ◽  
J. A. Bellan ◽  
T. R. Higuera ◽  
P. J. Kadowitz

Cardiovascular and pulmonary responses to sarafotoxin (S) 6a and S6c were investigated in the anesthetized cat. Intravenous injections of the peptides in doses of 0.1-1.0 nmol/kg caused decreases or biphasic changes in arterial pressure (AP) and increases in central venous pressure, pulmonary arterial pressure (PAP), and cardiac output (CO). Secondary decreases in CO were observed in response to higher doses, and biphasic changes in systemic (SVR) and pulmonary (PVR) vascular resistances were observed. Under constant-flow conditions, the peptides only increased pulmonary lobar arterial perfusion pressure and lobar vascular resistance. AP responses to S6a, S6c, endothelin (ET)-1, ET-2, vasoactive intestinal contractor (VIC), and Lys7-ET-1 were similar, whereas AP responses to S6b and ET-3 were similar. S6a, S6b, S6c, ET-1, ET-2, ET-3, VIC, Lys7-ET-1, and big ET-1 increased PAP. S6a and S6c increased distal aortic and superior mesenteric arterial (SMA) blood flow and caused biphasic changes at the highest doses. Under constant-flow conditions, S6a and S6c produced dose-dependent biphasic changes in hindquarters perfusion pressure. Changes in SVR and PVR in response to the peptide were not affected by hexamethonium, glyburide, or meclofenamate, indicating that responses are independent of autonomic reflexes, activation of ATP-regulated K+ channels, or release of cyclooxygenase products. In contrast, N-nitro-L-arginine methyl ester decreased hindquarters vasodilator response to S6a and S6c. The present data show that S6a and S6c produce both vasodilation and vasoconstriction in the systemic vascular bed and increase lobar vascular resistance and that hindquarters vasodilator responses are mediated, in part, by the release of endothelium-derived relaxing factor.


2007 ◽  
Vol 293 (5) ◽  
pp. L1306-L1313 ◽  
Author(s):  
Jasdeep S. Dhaliwal ◽  
David B. Casey ◽  
Anthony J. Greco ◽  
Adeleke M. Badejo ◽  
Thomas B. Gallen ◽  
...  

The small GTP-binding protein and its downstream effector Rho kinase play an important role in the regulation of vasoconstrictor tone. Rho kinase activation maintains increased pulmonary vascular tone and mediates the vasoconstrictor response to nitric oxide (NO) synthesis inhibition in chronically hypoxic rats and in the ovine fetal lung. However, the role of Rho kinase in mediating pulmonary vasoconstriction after NO synthesis inhibition has not been examined in the intact rat. To address this question, cardiovascular responses to the Rho kinase inhibitor fasudil were studied at baseline and after administration of an NO synthesis inhibitor. In the intact rat, intravenous injections of fasudil cause dose-dependent decreases in systemic arterial pressure, small decreases in pulmonary arterial pressure, and increases in cardiac output. l-NAME caused a significant increase in pulmonary and systemic arterial pressures and a decrease in cardiac output. The intravenous injections of fasudil after l-NAME caused dose-dependent decreases in pulmonary and systemic arterial pressure and increases in cardiac output, and the percent decreases in pulmonary arterial pressure in response to the lower doses of fasudil were greater than decreases in systemic arterial pressure. The Ca++ entry blocker isradipine also decreased pulmonary and systemic arterial pressure in l-NAME-treated rats. Infusion of sodium nitroprusside restored pulmonary arterial pressure to baseline values after administration of l-NAME. These data provide evidence in support of the hypothesis that increases in pulmonary and systemic vascular resistance following l-NAME treatment are mediated by Rho kinase and Ca++ entry through L-type channels, and that responses to l-NAME can be reversed by an NO donor.


1990 ◽  
Vol 258 (5) ◽  
pp. H1550-H1558
Author(s):  
R. K. Minkes ◽  
P. J. Kadowitz

Cardiovascular responses to endothelin 2 (ET-2) and sarafotoxin 6b (S6b) were investigated in the cat. ET-2 (0.1-1 nmol/kg iv) decreased or elicited biphasic changes in arterial pressure (AP), whereas S6b (0.1-1 nmol/kg iv) only decreased AP. Central venous pressure (CVP), cardiac output (CO), and pulmonary arterial pressure (PAP) were increased. ET-2 produced biphasic changes in systemic vascular resistance (SVR), whereas S6b decreased SVR at the two lower doses and caused a biphasic change at the 1 nmol/kg dose. The effects of ET-1 and ET-2 were similar, whereas the effects of S6b were similar to ET-3. ET-2 and S6b had small effects on right ventricular contractile force and caused transient increases in heart rate. Distal aortic blood flow was increased in response to all doses of both peptides, whereas increases in carotid blood flow were observed only in response to the higher doses of ET-2 and S6b. ET-2 produced dose-dependent decreases in superior mesenteric artery (SMA) blood flow, whereas decreases in SMA flow in response to S6b were observed only at the 1 nmol/kg dose. Renal blood flow was decreased significantly only at the higher doses of ET-2 and S6b. The present data show that ET-2 and S6b can produce both vasodilation and vasoconstriction in the systemic and regional vascular beds of the cat and demonstrate previously unrecognized vasodilator activity in response to S6b. It is concluded that ET-2 and S6b produce complex cardiovascular responses in the anesthetized cat.


2010 ◽  
Vol 299 (4) ◽  
pp. H1153-H1159 ◽  
Author(s):  
Adeleke M. Badejo ◽  
Vaughn E. Nossaman ◽  
Edward A. Pankey ◽  
Manish Bhartiya ◽  
Chandrika B. Kannadka ◽  
...  

BAY 41-8543 is a nitric oxide (NO)-independent stimulator of soluble guanylyl cyclase (sGC). Responses to intravenous injections of BAY 41-8543 were investigated under baseline and elevated tone conditions and when NO synthase (NOS) was inhibited with Nω-nitro-l-arginine methyl ester (l-NAME). Under baseline conditions, intravenous injections of BAY 41-8543 caused small decreases in pulmonary arterial pressure, larger decreases in systemic arterial pressure, and increases in cardiac output. When pulmonary arterial pressure was increased to ∼30 mmHg with an intravenous infusion of U-46619, intravenous injections of BAY 41-8543 produced larger dose-dependent decreases in pulmonary arterial pressure, and the relative decreases in pulmonary and systemic arterial pressure in response to the sGC stimulator were similar. Treatment with l-NAME markedly decreased responses to BAY 41-8543 when pulmonary arterial pressure was increased to similar values (∼30 mmHg) in U-46619-infused and in U-46619-infused plus l-NAME-treated animals. The intravenous injection of a small dose of sodium nitroprusside (SNP) when combined with BAY 41-8543 enhanced pulmonary and systemic vasodilator responses to the sGC stimulator in l-NAME-treated animals. The present results indicate that BAY 41-8543 has similar vasodilator activity in the systemic and pulmonary vascular beds when pulmonary vasoconstrictor tone is increased with U-46619. These results demonstrate that pulmonary and systemic vasodilator responses to BAY 41-8543 are significantly attenuated when NOS is inhibited by l-NAME and show that vasodilator responses to BAY 41-8543 are enhanced when combined with a small dose of SNP in l-NAME-treated animals. The present results are consistent with the concept that pulmonary and systemic vasodilator responses to the sGC stimulator are NO-independent; however, the vasodilator activity of the compound is greatly diminished when endogenous NO production is inhibited with l-NAME. These data show that BAY 41-8543 has similar vasodilator activity in the pulmonary and systemic vascular beds in the rat.


2011 ◽  
Vol 300 (3) ◽  
pp. H792-H802 ◽  
Author(s):  
Edward A. Pankey ◽  
Manish Bhartiya ◽  
Adeleke M. Badejo ◽  
Umair Haider ◽  
Johannes-Peter Stasch ◽  
...  

4-({(4-Carboxybutyl)[2-(5-fluoro-2-{[4′-(trifluoromethyl)biphenyl-4-yl]methoxy}phenyl)ethyl]amino}methyl)benzoic acid (BAY 60–2770) is a nitric oxide (NO)-independent activator of soluble guanylyl cyclase (sGC) that increases the catalytic activity of the heme-oxidized or heme-free form of the enzyme. In this study, responses to intravenous injections of the sGC activator BAY 60–2770 were investigated under baseline and elevated tone conditions induced by the thromboxane mimic U-46619 when NO synthesis was inhibited by Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME), when sGC activity was inhibited by 1H-[1,2,4]-oxadizaolo[4,3]quinoxaline-1-one (ODQ), an agent that oxidizes sGC, and in animals with monocrotaline-induced pulmonary hypertension. The intravenous injections of BAY 60–2770 under baseline conditions caused small decreases in pulmonary arterial pressure, larger decreases in systemic arterial pressure, and no change or small increases in cardiac output. Under elevated tone conditions during infusion of U-46619, intravenous injections of BAY 60–2770 caused larger decreases in pulmonary arterial pressure, smaller decreases in systemic arterial pressure, and increases in cardiac output. Pulmonary vasodilator responses to BAY 60–2770 were enhanced by l-NAME or by ODQ in a dose that attenuated responses to the NO donor sodium nitroprusside. ODQ had no significant effect on baseline pressures and attenuated pulmonary and systemic vasodilator responses to the sGC stimulator BAY 41–8543 2-{1-[2-(fluorophenyl)methyl]-1H-pyrazolo[3,4-b]pyridin-3-yl}-5(4-morpholinyl)-4,6-pyrimidinediamine. BAY 60–2770 and sodium nitroprusside decreased pulmonary and systemic arterial pressures in monocrotaline-treated rats in a nonselective manner. The present data show that BAY 60–2770 has vasodilator activity in the pulmonary and systemic vascular beds that is enhanced by ODQ and NOS inhibition, suggesting that the heme-oxidized form of sGC can be activated in vivo in an NO-independent manner to promote vasodilation . These results show that BAY 60–2770 and sodium nitroprusside decreased pulmonary and systemic arterial pressures in monocrotaline-treated rats, suggesting that BAY 60–2770 does not have selective pulmonary vasodilator activity in animals with monocrotaline-induced pulmonary hypertension.


1993 ◽  
Vol 2 (4) ◽  
pp. 287-292 ◽  
Author(s):  
M. G. Clement ◽  
M. Dimori ◽  
M. Albertini

The haemodynamic and respiratory responses caused by i.v. administration of endothelin-1 (ET-1) (20–100 pmol/kg) were studied in anaesthetized spontaneously breathing pigs. Intravenous bolus administration of synthetic ET-1 (40–100 pmol/kg) caused a transient decrease followed by a long-lasting increase in mean pulmonary arterial pressure and dose dependent vasoconstriction both in the systemic and pulmonary circulations. The effect on pulmonary arterial pressure was biphasic, with an initial transient fall followed by a long-lasting dose dependent increase. A biphasic response of the systemic mean arterial pressure was demonstrated only at a high dose of ET-1 (100 pmol/kg). ET-1 administration did not significantly change breathing pattern or phasic vagal input, but caused a significant decrease in passive compliance. Passive resistances or active compliance and resistances of the respiratory system were not modified. These results suggest that in the pig ET-1 is a more potent constrictor of vascular than of bronchial smooth muscle. The vasoconstrictor activity was greater in the pulmonary than the systemic circulations.


1992 ◽  
Vol 263 (6) ◽  
pp. H1659-H1669 ◽  
Author(s):  
R. K. Minkes ◽  
T. J. McMahon ◽  
T. R. Higuera ◽  
W. A. Murphy ◽  
D. H. Coy ◽  
...  

Systemic and pulmonary vascular responses to pituitary adenylate cyclase-activating polypeptide (PACAP), a novel peptide with 68% sequence homology to vasoactive intestinal peptide (VIP), were investigated in the anesthetized cat. Intravenous injections of PACAP in doses of 0.1–3.0 nmol/kg produced decreases in arterial pressure (AP) at low doses and biphasic changes (decreases followed by increases) at higher doses, which were accompanied by increases in central venous pressure (CVP) and cardiac output (CO), and decreases and biphasic changes in systemic vascular resistance (SVR). In contrast, VIP in doses of 0.1-3.0 nmol/kg produced only dose-dependent decreases in AP and SVR and produced little change in CVP and CO. PACAP produced increased pulmonary arterial pressure (PAP), left atrial pressure (LAP), and increases in pulmonary vascular resistance (PVR). PACAP increased heart rate (HR) and right ventricular contractile force (RVCF), while VIP had no effect. Increases in AP and SVR in response to PACAP were changed to decreases following the administration of phentolamine or after adrenalectomy. Under constant flow conditions, PACAP and VIP produced dose-dependent decreases in lobar arterial pressure when tone was elevated, with PACAP being threefold more potent than VIP. Meclofenamate and nitro-L-arginine methyl ester (L-NAME) had no effect on pulmonary responses to the peptides. PACAP produced dose-dependent biphasic changes in hindquarters perfusion pressure, whereas VIP produced only decreases that were unchanged by indomethacin, L-NAME, and glibenclamide. Phentolamine and adrenalectomy eliminated the hindquarters pressor response to PACAP and D-Phe2-VIP, a VIP antagonist, reduced responses to VIP but not to PACAP. These data suggest that responses to PACAP and VIP are mediated by distinct receptors and that pressor responses to PACAP are due to the release of catecholamines from the adrenal gland.


2005 ◽  
Vol 109 (2) ◽  
pp. 209-215 ◽  
Author(s):  
Theodoros Maltaris ◽  
Fortunato Scalera ◽  
Dietmar Schlembach ◽  
Inge Hoffmann ◽  
Andreas Mueller ◽  
...  

The present study was designed to examine the effects of ET-1 (endothelin-1) and serum from PE (pre-eclamptic), HP (healthy pregnant) and HNP (healthy non-pregnant) women on uterine arterial perfusion pressure and uterine contractility. Swine uteri (n=25) were perfused for a period of up to 11 h, with the aim being to preserve a viable organ. Various concentrations of ET-1 as well as serum from PE, HP and HNP women (n=10 per group) were administered to the perfused swine uteri and IUP (intrauterine pressure) and IAP (intra-arterial pressure) were recorded. ET-1 produced dose-dependent increases in IUP and IAP. The ET-1 concentration in serum was higher in serum from PE women than in HP and HNP women (P>0.05). Administration of all serum samples had a contractile effect on the swine uterus, with the greatest effect being seen in HNP women (12.8±5.3 mmHg), followed by PE (9.06±4.2 mmHg) and HP (6.1±4.1 mmHg) women. Statistically significant differences were observed between HNP and PE women (P=0.048), and PE and HP women (P=0.021). Increases in IAP following administration of serum from PE women (48.8±20.0 mmHg) were significantly higher (P=0.024) compared with the effect of serum from HP women (28.4±13.7 mmHg). In conclusion, the findings show that serum from PE women has significant vasoconstrictive and oxytocic effects compared with serum from HP women. In pre-eclampsia, the balance between vasorelaxing and vasoactive substances is disturbed.


Sign in / Sign up

Export Citation Format

Share Document