Indian Journal of Pharmacology Medknow Publications on behalf of Indian Pharmacological Society ISSN: 0253-7613 EISSN: 1998-3751 Vol. 41, Num. 1, 2009, pp. 56-56

Indian Journal of Pharmacology, Vol. 41, No. 1, January-February, 2009, pp. 56

Correspondence

Coronary flow and perfusion pressure

Kumar Pradeep, Goyal Manish

Department of Physiology, CSM Medical University, Lucknow
Correspondence Address:Department of Physiology, CSM Medical University, Lucknow
jenypradeep2002@yahoo.com

Code Number: ph09016

Related Article: ph08026

Sir

I read carefully an article published in the Indian Journal of Pharmacology, Apr 2008 vol. 40 Issue 2, entitled ′Effects of low level lead exposure on blood pressure and function of the rat isolated heart′. ^[1]

The author has stated that the sub chronic exposure of lead does not show significant change in coronary flow in isolated perfused rat heart. It is well established that when oxygen consumption is kept constant, coronary blood flow is constant, independent of the coronary arterial pressure variations. When the pressure is kept constant, the flow varies linearly, with variations in oxygen consumption. ^[2] Variations in coronary arterial flow are directly coupled to the contraction-related intramural blood volume variations. ^[3] The interaction between flow variations and contraction is referred to as the intramyocardial pump. ^[4] Various metabolic substances, including vasodilators, produced locally at increased heart rate, can affect the perfusion pressure. ^[5] Therefore, to asses the coronary flow, tachycardia and positive inotropy is observed in this study. It is essential to keep constant perfusion pressure in isolated heart model, which was not done by the author. Hence, the author′s statement is not justified.

References

1.	Reza B, Ali N, Azhdar H, Alireza A, Ali K. Effects of low-level lead exposure on blood pressure and function of the rat isolated heart. Indian J Pharmacol 2008;40:69-72.   Back to cited text no. 1     [BIOLINE]
2.	Vergroesen I, Noble MI, Spaan JA. Intramyocardial blood volume change in first moments of cardiac arrest in anesthetized goats. Am J Physiol Am 1987;253:H307-16.  Back to cited text no. 2
3.	Vergroesen I, Noble MI, Wieringa PA, Spaan JA. Quantification of O2 consumption and arterial pressure as independent determinants of coronary flow. Am J Physiol Br 1987;252:H545-53.  Back to cited text no. 3
4.	Dankelman J, Van der Ploeg CP, Spaan JA. Transients in myocardial O2 consumption after abrupt changes in perfusion pressure in goats. Am J Physiol 1996;270:H492-9.   Back to cited text no. 4  [PUBMED]  [FULLTEXT]
5.	Cornelissen AJ, Dankelman J, VanBavel EM, Spaan JA. Balance between myogenic, flow-dependent, and metabolic flow control in coronary arterial tree: A model study. Am J Physiol 2002;282:H2224-37.  Back to cited text no. 5

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