Toxicology, 4 (1975) 165--169 © Elsevier/North-Holland, Amsterdam -- Printed in The Netherlands
TOXICOLOGICAL EFFECTS OF INTRAVENOUS ADMINISTRATION OF PYRIDINE IN ANAESTHETIZED DOGS
H. VENKATAKRISHNA-BHATT,M.P. SHAH and S.K. KASHYAP Division o f Medical and Industrial Toxicology, National Institute o f Occupational Health, Ahmedabad 380 016 (India)
(Received October 5th, 1974)
SUMMARY In 17 anaesthetized dogs effects on blood pressure, respiration and biochemical changes in blood, i.e. serum glutamic oxaloacetic transaminase (SGOT), alkaline phosphatase (Alk.Pase), and urea, after intravenous administration of pyridine at various dose levels of 88 to 880 mg/kg body weight (LD5 to LDso) are reported. Commonly observed toxicity signs and symptoms are due to action of pyridine on the nervous system. There is no direct evidence of lowering of blood pressure. Lowering of blood pressure is noticed only at lethal doses and is accompanied by marked tachycardia. Death is due to respiratory failure. The significant biochemical changes are increase in SGOT and blood urea (p < 0.01) and decrease in serum Alk.Pase (p < 0.01).
INTRODUCTION Pyridine is an industrial solvent used in the manufacture of nicotinic acid, sulpha drugs, disinfectants, dyestuffs, rubber and paint industries, chemicals and explosives. Earlier reports based on animal studies indicate that it causes gastrointestinal upsets in the form of retching and vomiting in dogs on oral administration [1], degenerative and necrotic changes of kidneys in rats [2] and loss of body weight in mice within three weeks' time [3]. Our clinical observations in a small group of workers in dye manufacturing industries, indicate lowering of blood pressure in workers occupationally exposed to this chemical. There are no reports on such effects in the literature. Therefore, it was considered desirable to investigate the effects of pyridine on
Abbreviations: Alk.Pase, alkaline phosphatase; SGOT, serum glutamic oxaloaeetic transaminase.
165
blood pressure employing dogs as experimental animals and simultaneously to study other acute toxic manifestations. MATERIALS AND METHODS
Experimental animals A total of 17 dogs of either sex weighing between 12 to 17 kg were used. The dogs were anaesthetized with a-chloralose (Merck}, 100 mg/kg body weight intravenously and maintained on a dose of 25 mg/kg during the period of experimentation. Test chemicals The pyridine (C6 HsN; BDH) dissolved in saline (0.85% NaCl) and made up to pH 7.0, was administered in serial doses of 88 mg, 176 mg, 440 mg, 660 mg and 880 mg/kg b o d y weight. In each animal blood pressure was recorded from a cannula placed into the left carotid artery connected to a mercury manometer, and the heart rates were recorded from the continuous electrocardiograph tracings from Lead II. The pulse was recorded from the femoral artery and respirations were recorded on a kymograph with the help of Mary's tambour. Biochemical estimations SGOT activity [4], serum Alk.Pase and blood urea [4] were estimated before and after the administration of pyridine. RESULTS
Toxic manifestations The c o m m o n l y observed manifestations are salivation, myosis, lacrimation, nasal secretion, micturition, cloudy cornea, apnoea and death by cardiac failure which invariably resulted after administration of a dose of 880 mg/kg body weight (equivalent to LD50 ) intravenously. Effects on blood pressure and respirations are shown in Fig. 1. The fall in blood pressure after a dose of 88 mg/kg (equivalent to LD5 ) is insignificant and there is no change in respiration. With doses of 176 and 440 mg/kg body weight (equivalent to LD10 and LD2 ~ ) the fall in blood pressure was of the order of 13 to 21% and this was accompanied by tachycardia i.e. the heart rate increased from an average of 83 to 160 beats per min. The respirations did not show any appreciable change except slight depression at the time of administration. Pyridine when administered at doses of 880 mg/kg (equivalent to LD50 ) resulted in a steep fall of blood pressure and marked tachycardia. Initially there was a significant increase in the respiratory rate which was followed by slowing in rate and an increase in amplitude and ending in tapering respirations resulting in apnoea and death in all the animals within 1 to 3 h.
166
W
°l
ioo,
W
~
~'~ ~ ~
....
T
t
Q.
m
N~
B
A
~ •
*~
C
: i'~,.:_ . ~
-r
t
$-
D
!
E
Fig. 1. Record of respiration (upper tracing) and blood pressure (middle tracing) in anaesthetized dogs. Time marks stand for 6 seconds. Arrows indicate the point where injections o f t h e pyridine were made. (A) Control; (B) After i.v. 88 mg/kg pyridine; (C) After i.v. 176 mg/kg pyridine; (D) After i.v. 440 mg/kg pyridine; (E) After i.v. 880 mg/kg pyridine.
In Table I, the results of biochemical changes in SGOT, Alk.Pase and blood urea before administration of pyridine and at various dose levels are shown. All these parameters show a statistically significant change (p < 0.01) at all the dose levels ranging from 88 to 880 mg/kg body weight.
167
TABLEI EFFECTS OF PYRIDINE ON SERUM GLUTAMIC OXALOACETIC TRANSAMINASE, SERUM DOGS
ALKALINE
PHOSPHATASE
AND
BLOOD
UREA
IN A N A E S T H E T I Z E D
All values after pyridine compared to normal readings show statistically significant difference (p L 0.01). Dose (mg/kg)
SGOT (I. U.) (mean values)
Serum Alk. Pase (K.A. Units) (mean values)
Blood urea (mg%) (mean values)
Normal 88 176 440 660 880
6 8 16 17 17.5 18
10.5 8.5 8.0 6.0 4.5 2.5
29 40 48.5 57 62 64
-+ 0.60 -~ 1.00 -+ 1.58 -* 1.70 -+ 2.34 -* 2.00
~ 1.04 *- 0.74 ~ 1.45 -- 0.86 ± 0.49 ~ 0.47
+- 4.58 -* 8.09 "- 7.34 -+ 7.54 -+ 4.30 ± 6.63
DISCUSSION
Pyridine is p h a r m a c o l o g i c a l l y active b y its a c t i o n o n t h e central n e r v o u s s y s t e m [ 5 ] . Meyer [6] r e p o r t e d i n j u r y t o t h e medulla. T o x i c m a n i f e s t a t i o n s like h e a d a c h e , vertigo, weakness o f limbs, t r e m o r s , sialorrhoea, i n v o l u n t a r y m i c t u r i t i o n and d e f a e c a t i o n a n d d e a t h f r o m r e s p i r a t o r y paralysis as o b s e r v e d b y us have also b e e n r e p o r t e d b y B r o w n i n g [ 7 ] . O u r o b s e r v a t i o n s o n b l o o d pressure s h o w i n g a fall o n l y at very high dose levels o f 176 m g / k g b o d y weight and a b o v e p o i n t s t o t h e possibility t h a t it is a s e c o n d a r y manifestation and n o t t h e p r i m a r y a c t i o n o f pyridine. A n y m a n i f e s t a t i o n s suggestive o f h y p o t e n s i o n i.e. giddiness, weakness, nervousness etc., o n e x p o s u r e t o p y r i d i n e are in reality d u e t o its a c t i o n o n the n e r v o u s s y s t e m . A significant change in S G O T , Alk.Pase and b l o o d urea s u b s t a n t i a t e t h e earlier r e p o r t [8] t h a t p y r i d i n e in high a n d lethal doses causes liver a n d k i d n e y d a m a g e . ACKNOWLEDGEMENTS T h e a u t h o r s are t h a n k f u l t o Dr. S.K. Chatterjee, D i r e c t o r , N a t i o n a l Institute o f O c c u p a t i o n a l Health, A h m e d a b a d f o r e n c o u r a g e m e n t and Prof. M.N. Jindal, Head o f the D e p a r t m e n t o f P h a r m a c o l o g y , B.J. Medical College, A h m e d a b a d , f o r p r o v i d i n g l a b o r a t o r y facilities. Technical assistance o f Shri R.S. C h u d a s a m a is g r a t e f u l l y a c k n o w l e d g e d . REFERENCES 1 2 3 4
W. His, Arch. Exptl. Pathol. Pharmacol., 22 (1887) 253. J.H. Baxter, Am. J. Pathol., 24 (1948) 503. J.H. Baxter and M.F. Mason, J. Pharmacol. Exptl. Therap., 91 (1947) 350. H. Varley, Practical Clinical Biochemistry, Vol. 4, Interscience, New York, 1967, pp. 293, 294,453, 158.
168
5 W.L. Sutton, Heterocyclic and miscellaneous nitrogen compounds, in D.W. Fassett and D.D° Irish (Eds.), Industrial Hygiene and Toxicology, Vol. 2, Interscience, New York, 1967, p. 2189. 6 A. Meyer, Berufskrankh., 43 (1950) 144. 7 E. Browning, Toxicity and Metabolism of Industrial Solvents, Elsevier, Amsterdam, 1965, p. 304. 8 R.A. Coulson and F.G. Brazda, Proc. Soc. Exptl. Biol. Med., 69 (1948) 480
169
TOXICOLOGICAL EFFECTS OF INTRAVENOUS ADMINISTRATION OF PYRIDINE IN ANAESTHETIZED DOGS
H. VENKATAKRISHNA-BHATT,M.P. SHAH and S.K. KASHYAP Division o f Medical and Industrial Toxicology, National Institute o f Occupational Health, Ahmedabad 380 016 (India)
(Received October 5th, 1974)
SUMMARY In 17 anaesthetized dogs effects on blood pressure, respiration and biochemical changes in blood, i.e. serum glutamic oxaloacetic transaminase (SGOT), alkaline phosphatase (Alk.Pase), and urea, after intravenous administration of pyridine at various dose levels of 88 to 880 mg/kg body weight (LD5 to LDso) are reported. Commonly observed toxicity signs and symptoms are due to action of pyridine on the nervous system. There is no direct evidence of lowering of blood pressure. Lowering of blood pressure is noticed only at lethal doses and is accompanied by marked tachycardia. Death is due to respiratory failure. The significant biochemical changes are increase in SGOT and blood urea (p < 0.01) and decrease in serum Alk.Pase (p < 0.01).
INTRODUCTION Pyridine is an industrial solvent used in the manufacture of nicotinic acid, sulpha drugs, disinfectants, dyestuffs, rubber and paint industries, chemicals and explosives. Earlier reports based on animal studies indicate that it causes gastrointestinal upsets in the form of retching and vomiting in dogs on oral administration [1], degenerative and necrotic changes of kidneys in rats [2] and loss of body weight in mice within three weeks' time [3]. Our clinical observations in a small group of workers in dye manufacturing industries, indicate lowering of blood pressure in workers occupationally exposed to this chemical. There are no reports on such effects in the literature. Therefore, it was considered desirable to investigate the effects of pyridine on
Abbreviations: Alk.Pase, alkaline phosphatase; SGOT, serum glutamic oxaloaeetic transaminase.
165
blood pressure employing dogs as experimental animals and simultaneously to study other acute toxic manifestations. MATERIALS AND METHODS
Experimental animals A total of 17 dogs of either sex weighing between 12 to 17 kg were used. The dogs were anaesthetized with a-chloralose (Merck}, 100 mg/kg body weight intravenously and maintained on a dose of 25 mg/kg during the period of experimentation. Test chemicals The pyridine (C6 HsN; BDH) dissolved in saline (0.85% NaCl) and made up to pH 7.0, was administered in serial doses of 88 mg, 176 mg, 440 mg, 660 mg and 880 mg/kg b o d y weight. In each animal blood pressure was recorded from a cannula placed into the left carotid artery connected to a mercury manometer, and the heart rates were recorded from the continuous electrocardiograph tracings from Lead II. The pulse was recorded from the femoral artery and respirations were recorded on a kymograph with the help of Mary's tambour. Biochemical estimations SGOT activity [4], serum Alk.Pase and blood urea [4] were estimated before and after the administration of pyridine. RESULTS
Toxic manifestations The c o m m o n l y observed manifestations are salivation, myosis, lacrimation, nasal secretion, micturition, cloudy cornea, apnoea and death by cardiac failure which invariably resulted after administration of a dose of 880 mg/kg body weight (equivalent to LD50 ) intravenously. Effects on blood pressure and respirations are shown in Fig. 1. The fall in blood pressure after a dose of 88 mg/kg (equivalent to LD5 ) is insignificant and there is no change in respiration. With doses of 176 and 440 mg/kg body weight (equivalent to LD10 and LD2 ~ ) the fall in blood pressure was of the order of 13 to 21% and this was accompanied by tachycardia i.e. the heart rate increased from an average of 83 to 160 beats per min. The respirations did not show any appreciable change except slight depression at the time of administration. Pyridine when administered at doses of 880 mg/kg (equivalent to LD50 ) resulted in a steep fall of blood pressure and marked tachycardia. Initially there was a significant increase in the respiratory rate which was followed by slowing in rate and an increase in amplitude and ending in tapering respirations resulting in apnoea and death in all the animals within 1 to 3 h.
166
W
°l
ioo,
W
~
~'~ ~ ~
....
T
t
Q.
m
N~
B
A
~ •
*~
C
: i'~,.:_ . ~
-r
t
$-
D
!
E
Fig. 1. Record of respiration (upper tracing) and blood pressure (middle tracing) in anaesthetized dogs. Time marks stand for 6 seconds. Arrows indicate the point where injections o f t h e pyridine were made. (A) Control; (B) After i.v. 88 mg/kg pyridine; (C) After i.v. 176 mg/kg pyridine; (D) After i.v. 440 mg/kg pyridine; (E) After i.v. 880 mg/kg pyridine.
In Table I, the results of biochemical changes in SGOT, Alk.Pase and blood urea before administration of pyridine and at various dose levels are shown. All these parameters show a statistically significant change (p < 0.01) at all the dose levels ranging from 88 to 880 mg/kg body weight.
167
TABLEI EFFECTS OF PYRIDINE ON SERUM GLUTAMIC OXALOACETIC TRANSAMINASE, SERUM DOGS
ALKALINE
PHOSPHATASE
AND
BLOOD
UREA
IN A N A E S T H E T I Z E D
All values after pyridine compared to normal readings show statistically significant difference (p L 0.01). Dose (mg/kg)
SGOT (I. U.) (mean values)
Serum Alk. Pase (K.A. Units) (mean values)
Blood urea (mg%) (mean values)
Normal 88 176 440 660 880
6 8 16 17 17.5 18
10.5 8.5 8.0 6.0 4.5 2.5
29 40 48.5 57 62 64
-+ 0.60 -~ 1.00 -+ 1.58 -* 1.70 -+ 2.34 -* 2.00
~ 1.04 *- 0.74 ~ 1.45 -- 0.86 ± 0.49 ~ 0.47
+- 4.58 -* 8.09 "- 7.34 -+ 7.54 -+ 4.30 ± 6.63
DISCUSSION
Pyridine is p h a r m a c o l o g i c a l l y active b y its a c t i o n o n t h e central n e r v o u s s y s t e m [ 5 ] . Meyer [6] r e p o r t e d i n j u r y t o t h e medulla. T o x i c m a n i f e s t a t i o n s like h e a d a c h e , vertigo, weakness o f limbs, t r e m o r s , sialorrhoea, i n v o l u n t a r y m i c t u r i t i o n and d e f a e c a t i o n a n d d e a t h f r o m r e s p i r a t o r y paralysis as o b s e r v e d b y us have also b e e n r e p o r t e d b y B r o w n i n g [ 7 ] . O u r o b s e r v a t i o n s o n b l o o d pressure s h o w i n g a fall o n l y at very high dose levels o f 176 m g / k g b o d y weight and a b o v e p o i n t s t o t h e possibility t h a t it is a s e c o n d a r y manifestation and n o t t h e p r i m a r y a c t i o n o f pyridine. A n y m a n i f e s t a t i o n s suggestive o f h y p o t e n s i o n i.e. giddiness, weakness, nervousness etc., o n e x p o s u r e t o p y r i d i n e are in reality d u e t o its a c t i o n o n the n e r v o u s s y s t e m . A significant change in S G O T , Alk.Pase and b l o o d urea s u b s t a n t i a t e t h e earlier r e p o r t [8] t h a t p y r i d i n e in high a n d lethal doses causes liver a n d k i d n e y d a m a g e . ACKNOWLEDGEMENTS T h e a u t h o r s are t h a n k f u l t o Dr. S.K. Chatterjee, D i r e c t o r , N a t i o n a l Institute o f O c c u p a t i o n a l Health, A h m e d a b a d f o r e n c o u r a g e m e n t and Prof. M.N. Jindal, Head o f the D e p a r t m e n t o f P h a r m a c o l o g y , B.J. Medical College, A h m e d a b a d , f o r p r o v i d i n g l a b o r a t o r y facilities. Technical assistance o f Shri R.S. C h u d a s a m a is g r a t e f u l l y a c k n o w l e d g e d . REFERENCES 1 2 3 4
W. His, Arch. Exptl. Pathol. Pharmacol., 22 (1887) 253. J.H. Baxter, Am. J. Pathol., 24 (1948) 503. J.H. Baxter and M.F. Mason, J. Pharmacol. Exptl. Therap., 91 (1947) 350. H. Varley, Practical Clinical Biochemistry, Vol. 4, Interscience, New York, 1967, pp. 293, 294,453, 158.
168
5 W.L. Sutton, Heterocyclic and miscellaneous nitrogen compounds, in D.W. Fassett and D.D° Irish (Eds.), Industrial Hygiene and Toxicology, Vol. 2, Interscience, New York, 1967, p. 2189. 6 A. Meyer, Berufskrankh., 43 (1950) 144. 7 E. Browning, Toxicity and Metabolism of Industrial Solvents, Elsevier, Amsterdam, 1965, p. 304. 8 R.A. Coulson and F.G. Brazda, Proc. Soc. Exptl. Biol. Med., 69 (1948) 480
169
